Hearthstone Wiki:Advanced rulebook project/Draft1

While most rules in Hearthstone are fairly easy to ascertain, when several effects, each with their own behaviours, are brought into conflict, things can get a little more complicated. This page aims to clarify the sequence of events in these circumstances, as well as explaining some commonly misunderstood interactions.

For information on the game's basic mechanics, see Gameplay, Minion, Abilities and Character.

'''Please note: most of the rules and orders stated on this page are mostly derived from personal observations and testing. Since no official rulebook has yet been released, these observations are by their nature fallible. This article also reflects an ongoing investigation of the game's behaviours, and as such is subject to change at any time.'''

''Note to editors: Due to the complex and hard to ascertain nature of the rules stated on this page, major adjustments to this page's contents are best made with references to support them, and/or should be discussed on the talk page first.

Why isn't there an official rulebook?
The game is designed to be quick and easy to learn, allowing new players to have grasped the basics by the end of the tutorial. This makes the game far more accessible, increasing the appeal of the game and allowing it reach many players who might not wish to invest the time and effort in learning a more complex ruleset.

Hearthstone is often compared with card games such as Magic: The Gathering, featuring highly complex and "extremely detailed" rulesets, with official comprehensive rulebooks which are regularly updated and consulted during tournaments. In contrast, Hearthstone 's simple rules allow new players to pick up the game in minutes, with a minimally challenging learning curve. This makes the game far more accessible and is designed to make it appeal to a broader audience.

In most intermediate Hearthstone play, there is relatively little uncertainty over the operation of the basic rules, obviating most of the need for a rulebook. This approach also helps to ease new players into the game; Basic cards are designed to be simpler than cards of other sets for this reason. In addition, because Hearthstone is a digital card game, the system itself instructs players of many of the basic rules of the game, such as highlighting all permitted moves in a turn, and preventing players from taking illegal actions. Tooltips for keywords further assist players in learning and remembering the basic rules.

However, while the main operations of the game are usually without uncertainty, there are still times when the precise results of actions can be unclear in advance, especially when several advanced effects are in play. For this reason, some players have called for an official rulebook to be included in the game.

The main reason developers have given for the lack of an official rulebook is the desire to keep the game's rules essentially simple, and the game itself accessible. While other card games may require players to regularly consult and interpret complex rules, Hearthstone is intended to be playable without such measures, and the addition of a rulebook would be contrary to this design goal, as well as potentially encouraging the game to develop in increasingly complex ways. Game designers such as Ben Brode have stated a desire to keep the game simple and accessible enough to be understood without such resources.

For the most part, the game can be understood and enjoyed without consulting an external reference. However, where things get a little more intricate, this page aims to explain the game's underlying mechanics.

Observed rules
As stated in the lead section, please note that the rules and structures found on this page are mostly based on personal observations and testing. As such, the information found here is fallible and subject to change at any time.

In addition, it should be noted that the advanced rules of Hearthstone are often inconsistent, and work slightly differently for different cards. This generally requires learning specific rules and behaviours for individual cards, although when several of these cards are involved in the same interaction, even expert players can have difficulty predicting the precise outcome.

Where possible, general rules have been outlined, along with specific examples, and references provided. For the behaviour of specific cards, see those card pages.

Player actions
While events in Hearthstone generally happen in a clear, if sometimes rapid sequence, the game's flexibility toward player interaction can cause some confusion. Rather than forcing the player to wait until each event has concluded before taking further action, the game allows players to take actions and even interact with targets at almost any time, provided the elements involved are already present. This cosmetic behaviour, designed to allow for flexibility and accessibility, can make it appear that the player is interrupting the sequence of events on the board, or that it is important to wait until animations have completed before taking the next action. However, this is not the case.

The main example of this behaviour is when playing cards; a player can play 3 minions from the hand in quick succession, and all 3 will land on the battlefield prior to the first minion's Battlecry activating. However, for game purposes the events will resolve in proper sequence; for example, if the first of the minions played was Dread Infernal, its Battlecry will not damage the other 2 minions, since they did not actually appear on the board until after the first minion's summoning had resolved. Similarly, a player can play a card in the middle of the resolution of a series of triggered events; the game will pause to allow the player to play the card, then continue with the pre-destined actions, ignoring the new card until the previous actions have resolved, and the new card's correct place in the sequence of events has been reached. The visual indications that these cards have been played is purely cosmetic; the actions have in fact been queued and will be put into effect when the proper point has been reached. The same is true for the 'End turn' button, which will visually activate immediately once clicked, even if several queued actions have yet to play out.

This behaviour reflects Hearthstone 's looseness when it comes to presentation and accessibility. The player is not usually restricted from taking actions until the previous event has completed, and with a little attention to detail the outcome of the event in progress can often be ascertained through minor board factors which have already changed to reflect the outcome, such as cards which can no longer be played, or valid minions which can suddenly no longer be targeted. Likewise, taking an action which will lead the game to end will cause all other actions to become unavailable immediately after the fatal action is taken, even though the events - including unforeseeable and randomised outcomes - have not yet played out. This is because the outcome has already been calculated; the game is simply playing out a graphical representation of the events taking place, for the player's benefit, and at a speed at which players can better follow and understand the flow of events.

This approach also allows players in most cases to take several actions in quick succession, without waiting for animations to complete. This can be critical when the turn timer is about to expire, and allows players to queue actions far more flexibly and conveniently. For example, playing a Mechwarper with 3 mana will immediately cause a 2 mana Annoy-o-Tron to become playable, even though its mana cost has not yet visually been reduced. Similarly, playing an Azure Drake with no other possible actions will cause the 'End Turn' button to immediately highlight - unless the card drawn is playable by the player that turn, in which case it will not. If the card is not playable that turn, the highlighting and "Job's done" announcement will occur immediately after playing the Drake, and well before the Drake has hit the board, since the outcome has already been calculated.

This behaviour is perhaps most noticeable in its absence - such as during a long round of animations during which the player is unable to take any actions. In some cases, this can lead to missed actions, due to the player leaving it too late to act, often due to underestimating the time required for the animations to complete. This experience highlights how flexible the game generally is with regard to actions and event ordering.

When player interaction is involved, appearances can therefore be a little out of time with the underlying events. Conversely, such superficial factors as the speed at which the player took the actions will not affect actual game play in any way - aside from missed opportunities, miscalculations, and misplays!

Health, buffs and taking damage
The basic process of dealing and receiving damage is simple: the appropriate number of points are deducted from the character's current Health value. However, the interactions between Health, buffs and damage are a little more complex.

The key underlying design is that any time a minion's maximum Health is increased, its current Health is increased by the same amount. A 1/1 minion gaining +1 Health becomes a 1/2. There is no distinction between a minion's 'natural' Health and Health granted through enchantments. Effects which grant a minion +X Health actually work by increasing the minion's maximum Health; their current is automatically increased by the same amount.

However, when a minion's maximum Health is reduced, its current Health is only reduced if it exceeds the new maximum. If a minion's current Health does not exceed the new maximum, it will not be reduced. Losing current Health due to a reduced maximum Health does not count as damage.

These rules can result in a net increase in current Health without any healing being done. For instance, an Injured Blademaster with 3 Health out of 7 maximum may be increased to 4 Health (and 8 maximum) by a friendly Stormwind Champion. If the Champion is then silenced, the Injured Blademaster's maximum Health would be returned to normal, but his current Health of 4 would not be reduced back down, since it did not exceed the maximum. Such increases in Health are not counted as healing, but can act to restore a damaged minion to full Health, and thus undamaged status.

Similarly, while most increases to a minion's Health occur through gaining enchantments, they can also come from removing enchantments such as Equality and Hunter's Mark which lower Health. For example, if a 5/5 Stranglethorn Tiger is reduced to 1 Health, affected by Equality, then silenced, the result will be a full Health 5/5 Stranglethorn Tiger. This is because all increases to maximum Health cause an equal increase to current Health; the removal of the Equality enchantment increases the Tiger's maximum Health by 4, and therefore increases its current Health by the same amount, resulting in a full Health minion. Regardless of the cause, any adjustments to a minion's maximum Health follow the same rules.

Enchantments
The basic rule for multiple enchantments or 'buffs' is that each is applied to the minion in the order in which they were granted. This order can be observed by mousing over the minion: the buffs applied first will be at the top of the list. This means that each enchantment will potentially act upon the consequences of the previous enchantments. This makes the order in which enchantments are applied significant.

When a temporary enchantment is removed without removing other enchantments, the consequences of the enchantment stack are therefore recalculated. For example, if a 6/9 Gahz'rilla has its Attack temporarily reduced to 4 by a Shrinkmeister, and then suffers damage, the order of the enchantment stack will result in a total of 8 Attack: (((6 - 2) * 2) = 8). At the end of the turn, the Shrinkmeister's buff will be removed, resulting in the Gahz'rilla's Attack increasing not by 2, but by 4, to a total of 12: ((6 * 2) = 12). If enchantments were not dynamically recalculated, the Gahz'rilla's Attack would instead be increased to 10, since its previous net result of +4 Attack had already been established prior to the removal of the Shrinkmeister's buff.

Auras
The exception to this general rule is auras, ongoing effects which grant enchantments to certain other minions as long as the aura minion is in play (and not silenced). Aura buffs appear to be applied after all other enchantments, even if the aura was in place prior to the other buffs being gained. Another way to think of it is that auras automatically, continuously reapply themselves, so that auras affecting a minion are always newer than any regular enchantments belonging to the minion. For the most part this behaviour prevents auras from being included in the calculations of other enchantments, but still allows them to be included in effect calculations such as Reversing Switch.

Auras are notable for not being removable through silencing the minion with the buff, but only the minion which is generating the aura. Internally, auras are coded as rules that modify the stats of other minions directly, rather than via an enchantment on each minion - whenever the game runs a state update (see below), it wipes the effects of all rules clean and re-applies every rule from scratch, so it's not possible for the game to "forget" to apply an aura. This also leads to auras always being applied 'on top' of enchantments.

If an aura minion is destroyed, its aura will not be removed until the end of the phase in which the minion was removed from the board. This means that a 2 Health Stormwind Champion's aura will save a Gnomish Engineer from a Flamestrike, even though the Champion itself is destroyed by the spell. This is due to how death is handled in Hearthstone, whereby death does not occur until after all other consequences of the event responsible have played out. For more information, see the State updates and Death and damage sections, below.

The classic example of how auras differ from other enchantments is Crazed Alchemist. His Battlecry sets a minion's Health to its current Attack value, and vice versa. This includes all modifications, such as damage and enchantments, including auras. However, once the new stat values have been set (by way of a new enchantment) any auras will then be reapplied, on top of the new values. The result of this is that auras are effectively counted twice, allowing stat-switching effects to cumulatively increase the minion's combined stats.

For example, consider the following:


 * 1) A Timber Wolf is summoned next to a 5/4 Lost Tallstrider; its aura improves the Lost Tallstrider to a 6/4.
 * 2) A Crazed Alchemist is then summoned, and its Battlecry applied to the Lost Tallstrider.
 * 3) The Crazed Alchemist swaps the Lost Tallstrider stats, resulting in a 4/6.
 * 4) The Timber Wolf's aura is then reapplied to the Lost Tallstrider, resulting in a 5/6.
 * 5) The combination of Timber Wolf and Crazed Alchemist has therefore resulted in a net gain of 1 stat point.

If another Crazed Alchemist were to be played on the Lost Tallstrider, its total stats would again increase by 1, thanks to the Timber Wolf's aura being reapplied following the switch.

State updates
At a programming level, applying damage, enchantments and auras and updating characters stats appears to be achieved through regular game state updates, occurring after most events or phase completions. In most situations, the result is that stats are almost always up-to-date, and are always automatically updated following events or event phases. However, in more complex situations, the dependence upon a state update to correct stats - especially those modified by auras - can have critical repercussions.

Stats update at the end of all major phases, and appear to be the last thing to be updated, before the system checks for deaths. One key consequence of this system is that stats are not immediately updated following deaths. For example, if a Raid Leader is destroyed and removed from the board, the aura buffs of friendly minions are not immediately removed; they will remain at their previous levels while all simultaneous consequences are calculated and play out. Only after all simultaneous consequences, namely Deathrattles and death-related effects, have been resolved, will the Raid Leader's aura buff be removed from the other minions.

When an aura grants Health, this behaviour can lead to an aura granted by an already destroyed minion saving the life of another minion, a moment before it is removed. For example, Stormwind Champion's buff can allow a 2 Health minion such as a Knife Juggler to survive the Deathrattle of an Explosive Sheep, even if the Champion was killed at the same time as the Sheep. The reason for this is that the stats are last updated immediately before deaths are checked for, at which point the Champion is at 0 Health, but has not yet died. Thus, when the Sheep's 2 damage is dealt to the Knife Juggler, it is still benefiting from the Champion's aura buff, giving it a total of 3 Health; as a result, the Sheep's Deathrattle reduces it to 1 Health, but does not destroy it. Once all Deathrattles have resolved, the game will once again perform a state update and, finding the Champion dead, will remove the buff from the Knife Juggler, reducing its maximum Health to 2, but not reducing its current Health of 1.

Another interesting consequence of this design lies in the one apparent exception: direct damage. When a characters suffers direct damage, such as from a damaging spell, or combat, their Health will be immediately adjusted to reflect the numerical value of the damage dealt; this value will also be displayed on a flash directly over the character. However, the change to the character's Health and state is not actually implemented until the next state update. The result is that dealt damage is displayed immediately, prior to other effects and prior to the next state update. As explored in the Player actions section, this is likely because when several effects occur within a single phase, having to wait till the end of the phase for damage to be shown would feel extremely disjointed and unnatural, not to mention unsatisfying. For example, if a Knife Juggler is triggered by an Unleash the Hounds, throwing 5 knives, having each knife hit its target without apparently dealing damage, then all targets' Health suddenly being altered simultaneously at the end of the turn, would be extremely odd. Since a Knife Juggler will not throw knives at a target which has already reached 0 Health, it might also make target selection confusing, since the target would still be shown as being at positive Health. The underlying process is therefore hastened visually for the convenience and comprehension of the player. However, this can lead to some confusing visual results.

This can be observed when Lord Jaraxxus is played against a player with both Repentance and Snipe in play (played in that order). When Lord Jaraxxus is played, the hero will be replaced; the summoning of Jaraxxus will then trigger Repentance, and the hero's Health will be reduced to 1; Snipe will then be triggered, dealing 4 damage to the hero; the result is a -3 Health hero, who is then destroyed. However, because Repentance does not deal damage but rather directly affects the hero's Health, its adjustment is not made immediately, but rather during the state update at the end of the phase. Meanwhile, the Snipe does deal direct damage and thus immediately impacts the hero's Health both with a flash graphic and a visual adjustment to the hero's displayed Health value. The result is that while the Repentance has no apparent immediate effect, the Snipe immediately reduces the hero to 11 Health; the Repentance is then applied, reducing the hero to -3 Health. This apparent sequence of events makes no sense with Repentance's actual function; if the secrets had in fact triggered in the opposite order, the result would be a 1 Health hero, who would not be destroyed. Thus the convenience of immediate damage display is revealed to be purely cosmetic, including the calculation of resulting Health values.

Within any given phase, the pattern therefore appears to be roughly as follows:


 * 1) The phase begins
 * 2) All triggers occur and resolve, one at a time
 * 3) States are updated
 * 4) The system checks for any deaths
 * 5) Any deaths will count as events, and the pattern will be repeated
 * 6) The phase will end

As a technical note, it is not yet entirely clear whether stats update at the end of every single phase, or only at the end of major phases. The reason is that in certain game processes, multiple series of triggers may play out before any stats are updated. This may reflect that the trigger series are in separate phases, but these phases are not individually considered major phases; or it may be that these series of triggers are in fact higher and lower priorities within a single phase. For example, Murloc Tidecaller always activates before Hobgoblin, regardless of order played - suggesting that it is in an earlier phase. However, if summoning a minion triggers both of these effects, stats will not be updated until after both have activated - suggesting that they share a phase. It is possible that the Murloc Tidecaller simply automatically has a higher priority than the Hobgoblin, and so despite sharing an activation phase, will always activate first.

While most ongoing effects appear to be updated only during the state updates, some non-aura effects appear to behave differently. For example, Mal'Ganis' hero Immune effect is removed immediately after his death, before any Deathrattles or death triggers. As a result, he will not protect the hero from any Deathrattles triggered by simultaneous deaths. For example, if a weakened Mal'Ganis and an Abomination are killed by a Flamestrike, the hero will lose the Immune effect before the Abomination's Deathrattle is triggered, and so will be damaged by it. However, it is worth noting that Mal'Ganis' aura does appear to follow normal behaviour, continuing to grant his buff to friendly Demons until the next state update, and potentially saving them from being destroyed by the Abomination's Deathrattle.

Sequence of events
One of the main uncertainties in understanding Hearthstone lies in understanding the precise order in which several simultaneously occurring events will take place.

A key point to understand is that when multiple events take place simultaneously, each event will occur, one at a time, in a specific order, before any of the events become fully resolved. What's more, actions that are caused by an event will take effect and resolve while the original event is occurring, and before it resolves. Each event also has three phases - starting, action and resolution - each of which may trigger different events, such as Secrets and triggered effects.

These somewhat cryptic statements can be broken down further:


 * 1) When an event happens, it will begin to take place, and enter its "current" or occurring phase.
 * 2) During this time the event is taking place, but has not yet happened.
 * 3) Any related triggers to the starting of the event will activate, and their consequences will play out. Examples include Counterspell, Mana Wyrm, Freezing Trap and Hobgoblin.
 * 4) If nothing has happened to prevent the event from taking place, the event will actually occur; for example, damage may be dealt to a minion, or a minion summoned.
 * 5) Any related triggers to the action of the event will activate. This includes effects which trigger from the event occurring, as well as those that trigger from the actual consequences of the action. Note that an event's action may have several phases of its own, each of which may trigger different types of effects. For a description of the phases of minion summoning, see Minion summoning, below.
 * 6) Any deaths will now be resolved, and the minions removed from the board. Note that this deaths do not take place immediately following the cause of death, but are held until all other consequences have played out.
 * 7) Any death-related triggers will play out, including Deathrattles. Examples include Dark Cultist, Avenge and Flesheating Ghoul.
 * 8) Once all actions and related consequences have taken place, the event will resolve, and is now considered completed.
 * 9) Any related triggers to the resolution of the event will activate, and their consequences will play out. Examples include Wild Pyromancer and Knife Juggler. Any Overload will also occur at this point.

Note that some types of triggers will activate immediately after the event, before it actually takes place; while others will activate after the event takes place; and some will not activate until after it has resolved. See the triggered effects section of this page for a breakdown.

Another result of these rules is that events in Hearthstone can become "nested", like a large equation: main event (triggered event (triggered event (triggered event) ) )

Each must resolve before the next can take place, but each may trigger further sub-events which must themselves resolve before the triggering event can resolve. This is the case even when several events are triggered at once: main event (triggered event A (triggered event (triggered event) ) triggered event B (triggered event) triggered event C )

This can sometimes lead to complex, several layer deep interactions.

Resolution
When multiple effects are triggered by the same event, or take place during the same phase, all effects will activate and play out before the phase resolves, and any deaths occur. This comprises the basic pattern of events in Hearthstone.

For example, because all consequences take effect before any results are resolved, it is possible for a minion or hero to momentarily be at 0 Health or even a negative amount of Health (e.g. -5 Health), before regaining Health through a simultaneous effect, and thus avoid dying. This allows matches to end in draws, with both players defeated by multiple simultaneous effects, even though one actually died before the other. For more details, see Death and damage, below.

Another example would be using Shadow Madness on an enemy Wild Pyromancer; although at the time the spell was cast the Pyromancer belonged to the opponent, by the time the spell resolves, the Pyromancer is under the control of the casting priest, with the result that its triggered effect will activate. This means that using Shadow Madness on a 1 Health Wild Pyromancer will result in the Pyromancer destroying itself before it can be used to attack.

For further details and examples of this behaviour with regard to multiple triggered effects, see Simultaneous triggered effects, below.

''Multiple effects from a single card are considered to happen simultaneously. All effects will therefore take effect before any deaths resolve.'' For example, a Sabotage will complete both its destroy effects (minion and then weapon) before the death of the minion, and then the weapon, are resolved - including any Deathrattles.

However, each will still play out in turn, and any consequences will occur, before the next component occurs. For example, an Arcane Missiles will play out each strike individually, including consequences such as triggering an Acolyte of Pain, or causing a minion to become destroyed, before moving on to the next strike. Once all components have completed, only then will any deaths be resolved, and consequences thereof played out. This functions in much the same way as simultaneous triggered effects, with each occurring before any resolutions take place.

There are currently two exceptions to the rules of resolution: Poison Seeds and Mimiron's Head. Minions destroyed by these cards' special effects have their deaths resolved immediately, in order to make room for the Treants or V-07-TR-0N to be summoned. The resolution of the deaths includes the activation of any Deathrattles, which will still take place before the Treants are summoned. If this were not the case, due to the 7 minion limit, a player who had 5 minions before Poison Seeds was played would gain only 2 Treants, while a player with 7 minions on the board would gain none. In essence, these cards have 2 action phases of resolution, one to destroy the old minions (followed by all resulting triggers such as Deathrattles) and then one to summon the new minion(s).

A final exception is hero death. Hero death only seems to be played out following all consequences of the lethal action, including all other deaths and Deathrattles and related effects. For example, if a player attacks a 2 Health opponent using a 1 Durability Powermace, the opponent will suffer 3 damage, reaching -1 Health; then the Powermace will be destroyed, and its Deathrattle will grant a buff to a friendly Mech (if any); and then the hero will be destroyed. This is different to the normal order of events, in which the hero would have been destroyed prior any other deaths, and certainly before any Deathrattles were resolved. For more information, see the Death and damage section.

Order of activation
When multiple triggered effects, secrets or Deathrattles are activated simultaneously, they will be activated in the order in which the effects were put into play. This applies to minions, weapons and secrets.

This can make order of play extremely important. For example, if a previously summoned Ogre Brute attacks against a paladin with Noble Sacrifice, if the secret was played before the Ogre Brute was summoned, it will activate first, summoning a Defender; the Ogre Brute's clumsy effect will then activate, giving him a chance to instead strike another target, including his original target, thus allowing him to bypass the secret's Taunt-like effect. However, if the Ogre Brute was played before the Noble Sacrifice, the clumsy effect will trigger first; Noble Sacrifice will then activate, and whichever target the Ogre Brute had selected, he will instead hit the Defender.

Transforming a minion will result in the new minion becoming last in the 'queue', since it has been freshly put into play.

Area of effect
As of Goblins vs Gnomes, AoE healing and damage effects affect all relevant targets at once, before any triggers take place. This means that a Circle of Healing will heal all minions before any Northshire Clerics will begin to activate. Once the action phase is complete, triggers will still activate in a specific order, either by order summoned or by placement.

Regardless of the order in which AoE effects impact targets, deaths and Deathrattles should always take place in the order in which the minions were summoned. For example, if the opponent uses Flamestrike to destroy 7 different targets while the controlling player has a Duplicate active, the minion which was summoned first should die first, and therefore be the one to activate the Duplicate and be copied into the player's hand.

Combat
Combat occurs in two distinct phases: preparing to attack; and attacking.

Combat will be cancelled if the attacking character dies or is removed from the board during the preparation phase. Like all actions, sending a character to attack first checks for any related triggers. These will activate in order before the preparation phase completes and the character is then able to connect with its target. This allows effects like Ogre Brute's card text or Misdirection to select a new target; effects like Freezing Trap to return a minion to the hand; and secrets like Explosive Trap to remove a minion from the board. Other less directly significant effects such as Snake Trap's summons will also activate first.

Any consequences from related triggers will therefore play out and resolve, potentially affecting the character and the board, prior to the attack actually occurring. This can have a variety of consequences:


 * The stats of the character or the target may be modified, such as by the death of a friendly Stormwind Champion, damage triggering a Amani Berserker's enrage effect, or card draw from a destroyed Loot Hoarder activating a Goblin Sapper's ongoing effect. In all cases the changes will be fully applied during the trigger phase, and will therefore be in place by the time the attack completes.
 * A new target may be selected, or control of the target may even be transferred to the other player. In either case the attack will continue as planned, even if that means trading damage with what is now a friendly minion.
 * The target and/or or attacking character may be destroyed. In either case, the attack will be aborted. This often has unexpected consequences on involved factors such as weapon Durability, as the attack was started but was not completed, meaning some elements will occur while others will not.
 * Through various means, other triggers may be activated, causing a range of outcomes including the above. For example, a Snake Trap will summon Snakes, which while not in themselves obstructing the attack, may cause the activation of a Knife Juggler, who may then deal fatal damage to the attacking character. Alternatively, the Knife Juggler may destroy an Explosive Sheep, who may destroy the attacking minion. Or, the Knife Juggler may hit an Acolyte of Pain, causing the controlling player to draw a Burrowing Mine, thus dealing the hero fatal damage and ending the game.

One exception to the normal order of events is hero health. While the system checks for hero deaths along with other deaths at the end of each phase, hero deaths will not complete until all other simultaneous deaths, Deathrattles and other related effects have played out. Therefore, if a hero is destroyed by effects triggered during the preparation phase, all other effects, as well as any other deaths, and any Deathrattles or other consequences of those deaths will be played out in full before the match ends. However, the game will end at the preparation phase, and combat itself will not occur; the attacking minion (if not destroyed) will not be allowed to reach their target, instead remaining suspended mid-attack until the player leaves the battlefield. This can be critical in cases where completing combat would cause the other hero to also be destroyed.

Card playing and spell casting
The process of playing a card - paying its mana cost and removing it from the player's hand - is completed before the card attempts to take effect. For example, a spell which is countered by Counterspell will still be removed from the hand, and will still cost its full mana cost. Likewise, Arcane Intellect removes itself from the player's hand before causing them to draw 2 more cards.

Minions likewise will not appear on the board or activate any Battlecries until after their card has been removed from the player's hand, and its mana cost paid. This is relevant for cards like Twilight Drake, which increases its Health by the number of cards in the player's hand - once it has itself been removed from the hand. Likewise, it is possible for a player with 6 cards to use a Stampeding Kodo's Battlecry to kill a Goblin Sapper; with 6 cards in hand the Sapper will be at 6 Attack, and cannot be targeted by the Kodo, but by the time the Kodo arrives on the board and activates its Battlecry, the player will have only 5 cards remaining in their hand, causing the Sapper's Attack to diminish to 2, and thus allowing it to be targeted and destroyed by the Kodo.

Triggered effects and secrets which activate from the playing of a card or minion from the hand, or from the casting of a spell, generally trigger immediately after the card is played, before it takes effect, and in the case of spells before the spell is cast. For example, Counterspell will not prevent a spell from activating other spell triggers such as Mana Wyrm, however it will prevent Wild Pyromancer from triggering; this is because the spell's cast has been countered, and thus never completes. However, there is one exception: Spellbender does not activate until after the spell has been cast successfully, although still before it can take effect. This allows a Counterspell to prevent a Spellbender from triggering.

There is no distinction in activation phase between effects which trigger from cards played, from spells cast, or from minions played from the hand. For example, if a player plays a Questing Adventurer, a Mana Wyrm, and then a second Questing Adventurer, before then casting Ice Lance, all 3 minions will be activated, in the order in which they were played.

Minion summoning
Following is the basic sequence of events for playing minions from the hand. The below sequence should also be roughly correct for the playing of non-minion cards, although several steps are exclusive to summoning.
 * Playing minions from the hand

NB: Card text does not necessarily accurately describe the precise event which causes an effect to trigger. Identical wording on two different cards may correspond to entirely different activation phases, and the wording may be contradicted by the phase in which the effect does in fact activate.

Note that every stage of the summoning process forms a 'phase' during which Hearthstone does not check for deaths. For example, if two Ship's Cannons or two Knife Jugglers trigger simultaneously, and the first kills an Abomination, the Abomination is not destroyed until the second one finishes firing. Similarly, if Dr. Boom is played, and each Boom Bot he summons triggers a Knife Juggler, only once the Battlecry resolves will newly dead minions trigger Deathrattles.

Note also that the summoned minion must still be alive at each stage for Hearthstone to continue processing the summoning. For example, if an Elven Archer kills itself by taking out an Unstable Ghoul with its Battlecry, a friendly Knife Juggler will not activate, nor will an enemy Snipe.


 * 1) The card is played, mana expended, and the minion summoning stage begins
 * 2) The minion itself appears physically on the board, and assumes the position selected for it.
 * 3) Triggers from the minion entering play will activate and play out at this point, e.g., Murloc Tidecaller,    Cobalt Guardian
 * 4) Certain triggers from the playing from the hand of the minion will activate and play out at this point, e.g., Hobgoblin, Questing Adventurer,  Illidan Stormrage
 * 5) For the first time during the summoning process, all minion stats will be re-calculated. This will take into account auras operating upon the summoned minion, and auras generated by the summoned minion.
 * 6) Certain triggers from the summoning of the minion will activate and play out at this point, e.g., Starving Buzzard,  Undertaker, intended behaviour of Warsong Commander
 * 7) Any Battlecry will be activated, take place, and resolve.
 * 8) Any Secrets triggered from the playing from the hand of the minion will activate and play out at this point, e.g. Mirror Entity, Repentance and Snipe. The current bugged behaviour of Warsong Commander also activates at this point.
 * 9) Certain triggers from the summoning of the minion will activate and play out at this point, e.g. Ship's Cannon
 * 10) The minion summoning resolves
 * 11) Any triggers from the resolution of the minion summoning/the minion entering play will activate and play out at this point, e.g., Knife Juggler, Sword of Justice.
 * 12) It appears that at the end of the phase in which the summoning process itself was initiated, a general check or 'catchup phase' is performed for any summoning-triggered effects which are now eligible but were not previously activated. For example Starving Buzzard will trigger at this point in response to the Battlecry of Druid of the Fang, or the Battlecry of a Faceless Manipulator if a Beast target is selected. The same appears to be true for Murloc Tidecaller in combination with Mirror Entity (see below). Note that this general check occurs following the above resolution check.   Note that this check takes place at the end of the phase which triggered the summoning, and not at the end of the summoning process itself. For example, Unleash the Hounds will cause a pair of friendly Starving Buzzards to trigger, but not until after all Hounds have been summoned, at which point they will take turns to activate for each Hound summoned; while the Boar summoned by Razorfen Hunter's Battlecry will trigger a Starving Buzzard before the Razorfen Hunter's summoning resolves. This check also takes place before the phase which triggered the summoning resolves; for example, a Starving Buzzard will always trigger before a Wild Pyromancer. The same 'general check' appears to also take place for minion deaths (see Deathlord/Flesheating Ghoul example, below).

NB: While stat updating is only listed once above, it is believed that stats (including auras) are updated after each event or phase completion, as part of game-wide updates. As a result, stats can additionally be expected to be updated following each significant step of the summoning process.

The process of summoning a minion appears to be very similar to the above process for playing a minion from the hand, except that most of the middle steps do not occur. In essence, it appears that summoning or putting a minion into the battlefield enters it into the above process, triggering those effects which activate from a minion entering play, but without triggering those which activate from a minion being summoned or played from the hand. Effects which activate from a minion being summoned do not activate in their usual phase, but instead in the 'catchup phase'. Thus a summon effect such as Mirror Image will still trigger Knife Juggler, but not an opponent's Snipe; and Dr. Boom's Battlecry will trigger Cobalt Guardian, but not Hobgoblin. This behaviour may be due to the "entering play" phase occurring outside the main summoning process, with the process itself then joined partway through, just after the Battlecry phase.
 * Summoning minions and transformation effects

Mid-summon transformation effects such as those of Druid of the Fang function as usual, by replacing the current minion with another, but continuing the process from the exact point the original minion was at. For example, if a player has a Starving Buzzard and a Knife Juggler on the board (played in that order), and plays Faceless Manipulator, targeting the Starving Buzzard, the Manipulator will transform before it triggers an enemy Mirror Entity. Once the enemy summon has resolved, the transformed Manipulator will then go on to trigger the Knife Juggler, before then activating the Buzzard. If the Manipulator worked by summoning a separate minion to itself, it would not activate the Mirror Entity, since summons do not activate that secret.


 * Notes

While the basic order of events is clearly discernible by observing the interactions of cards such as those listed on the right, the point at which summoning-related triggered effects are activated is clearly highly variable. Some activate prior to auras, others immediately afterwards, and others still once Battlecries and card text have been applied.

It also appears that there may be a general check at the end of the overall summoning process, in which effects which were not present earlier in the process can be triggered. This allows any effects now in play which would have triggered during an earlier stage of the summoning process to be activated. In all known cases the minion appears to activate at the very end of the process, despite the fact that they would normally have activated in an earlier phase. For example:


 * 1) Murloc Tidecaller is played, beginning its summoning stage
 * 2) The minion appears on the board
 * 3) The opponent's Mirror Entity is activated
 * 4) Mirror Entity summons a copy Murloc Tidecaller
 * 5) The first Murloc Tidecaller's triggered effect is activated by the summoning of the second Murloc Tidecaller, granting it +1 Attack
 * 6) The second Murloc Tidecaller's triggered effect is activated by the summoning of the first Murloc Tidecaller, granting it +1 Attack
 * 7) The result is a 2/2 Murloc Tidecaller on each side of the board

If the minions did not check for summoning at multiple points, only one of the minions would gain the +1 Attack, not both. Note also that the effects are not triggered simultaneously; each triggers in turn from the summoning of the other minion.

Another unexpected consequence of the above order for playing minions is that triggers from the minion's summoning or its Battlecry will take place (and resolve) before the minion's summoning has resolved.

This behaviour can be seen clearly when using Sword of Justice in combination with minions such as Murloc Tidehunter whose Battlecry summons another minion; the additional minion (in this case Murloc Scout) will be buffed first, and the original minion will be buffed second. This can be critical when the Sword of Justice has only 1 Durability remaining, as only the Battlecry-summoned minion will gain the buff (as opposed to the original minion), a conclusion which may be contrary to expectations since the latter minion was summoned first. However, if the Murloc Tidehunter is played while a Murloc Tidecaller is on the board, the Tidecaller will gain buffs from both the Tidehunter and the Scout before the Scout has even appeared on the board.

Another example would be that if a Mad Scientist is killed by the Battlecry of a Stampeding Kodo and puts into play a Mirror Entity, the Mirror Entity will then copy the Stampeding Kodo. This is because the interaction between the Kodo and the Mad Scientist, the triggering of the Mad Scientist's Deathrattle, and the subsequent putting into play of the Mirror Entity, all take place during the Battlecry phase. Once the Kodo's Battlecry has completed, the system then checks for any appropriate triggers, and finds the Mirror Entity, which is then activated, producing a copy of the Stampeding Kodo.

Death and damage
When minions are killed, there is a specific sequence in which their deaths are resolved.


 * 1) The events in question play out: the minion/s take damage (or suffer a Destroy effect), and their stats and appearance are altered. Note that in the case of multiple targets, all damaged characters will take damage simultaneously.
 * 2) For each minion that takes damage, any triggers from that damage will take place and resolve - for example Acolyte of Pain's triggered effect. All triggers from each minion will resolve before any triggers for the next damaged minion will begin to resolve. Both the order of the minions and the order of the triggers match the order in which the minions or effects were put into play.
 * 3) The game will perform a state update, changing all minion stats to reflect any changes to enchantments and auras.
 * 4) Any minions which have 0 or lower Health are now destroyed, and removed from the board.
 * 5) Each death will now be resolved, including the activation of any death-related effects - this includes the minion's own Deathrattle, triggered effects such as Cult Master, and Secrets such as Duplicate. Resolution takes place one minion at a time, in order in which the minions entered play. As each death is resolved, all eligible triggered events will play out in the order in which the effect entered play, including the minion's Deathrattle, Secrets and other effects. Each effect will play out individually and resolve, before the next activates. Once all related effects have played out for the minion, the next minion's death will begin to resolve.
 * 6) Once all deaths have resolved, the game will check again for any other minions which now have 0 or lower Health, and if any are found, the process repeats itself.
 * 7) Once there are no more deaths to take place, the surrounding phase will complete, such as with the resolution of the spell or combat which caused the first death/s.

Note that all triggered effects from the death of a minion will play out in the order in which they were put into play, regardless of type of effect. For example, if a mage plays Duplicate followed by Abomination, and the Abomination is then destroyed on the opponent's turn, the Duplicate will activate before the Abomination's own Deathrattle; while if the Abomination was played first, its Deathrattle will activate first, followed by the secret. Deathrattles do not gain any special priority.

However, there is at least one exception to this order: Redemption always activates after any death-related effects have played out, regardless of the order in which the effects were put into play.

One critical detail is that the game only checks for deaths after each phase has completed. In fact, the game checks for death at the end of each phase, or round of triggers.

For example, as detailed in the Resolution section, a character which is simultaneously damaged to 0 Health or below and then healed back to above 0 Health, will not be destroyed. For example, a 2 Health hero attacking with a Truesilver Champion into an Explosive Trap will survive, since both the 2 healing and the 2 damage occur in the same phase, before death is checked for. This is because all simultaneous effects are played out and resolved before the phase ends; and the game does not check for deaths mid-phase. By the time the game checks to see if anything has reached 0 Health, the character has regained a positive Health value, and therefore has no reason to be destroyed.

As described in the State updates section, it is also worth noting that the game does not update minion stats immediately after minions are removed from the board, but only once all triggers from those deaths have played out. This can allow Health-buffing auras like Stormwind Champion to save the lives of a 2 Health minion which would have been destroyed by the simultaneous death of minions such as Abominations; the minion is still buffed to 3 Health at the time it suffers damage from the Abomination's Deathrattle, despite the generating minion already being dead.

However, once a death has been successfully recognised, subsequent events cannot undo it. A common example is that a 2 Health hero attacking a Zombie Chow with a non-healing weapon will see the player destroyed, despite receiving the Zombie Chow's healing Deathrattle. The reason is that the hero's death was registered at the same time that the Zombie Chow's was; all consequences, including the Deathrattle, were then allowed to play out, but the hero's death had already been registered and thus the Zombie Chow's healing was unable to save the hero.

The above example also illustrates that hero death is a small exception to the normal order of resolution. If at any point the current phase and all consequences conclude with a hero at 0 Health, the hero will be marked for destruction. However, the hero will not be destroyed at that point; any minion deaths and Deathrattles will play out and resolve prior to the destruction of 0 Health heroes. The logic of this appears to be that hero death ends the game, and thus even once registered, it does not take place until all other consequences have played out. This allows for triggered effects to cause the simultaneous death of both heroes, which would otherwise have resolved immediately after the game completed, and is likely designed to feel more natural, since those consequences had already been set in motion. The one exception to this is combat, which has two distinct phases: preparation and actual combat. As a result, if a hero is destroyed by the activation of an enemy secret caused by a minion preparing to attack, the game will end there, without allowing combat to complete.

It should also be noted that because Deathrattles follow deaths, and the game does not check for deaths until all consequences have completed, a Deathrattle that causes the death of another minion, which itself possesses a Deathrattle, will not see the second minion's Deathrattle activated until all consequences of the first minion's death have completed. Essentially, unlike most events in Hearthstone, deaths are not nested; a death that results from another death will not play out until the first has resolved. However, all deaths, and any deaths triggered by those deaths, will be resolved before the triggering action or phase itself resolves.

Deathrattles and death-related effects
Deathrattles and death-related effects take place after damage has been exchanged and minions (and/or weapons) have been destroyed and destroyed from the board. This prevents Deathrattles from acting upon other minions which were destroyed in the same combat. It also prevents several simultaneous events from acting upon consequences of Deathrattles or other triggered events. The same is true for secrets and triggered effects which are activated from death, such as Duplicate and Cult Master, which are treated exactly the same as Deathrattles.

For example, playing a Flamestrike against a Northshire Cleric and a Dark Cultist will result in both minions being destroyed, regardless of the Dark Cultist's Deathrattle. This is because the Deathrattle will not activate until after both minions have been removed from the board, preventing it from being granted to the Cleric. Similarly, an Avenging Wrath that destroys a Harvest Golem will complete its damage dealing before its Deathrattle summons Damaged Golem, preventing the spell from destroying the latter minion. This behaviour affords such 'sticky' minions better survivability against multiple impact attacks.

This order also prevents minions with Destroy-related triggered effects from gaining Health or other protection from the simultaneous deaths of other minions. For example, mages can rest assured that playing Flamestrike against a base-value Scavenging Hyena and 6 Hounds will result in the destruction of all enemy minions. If the deaths were resolved one at a time, the Scavenging Hyena (if summoned after the Hounds) would gain so much Health from the deaths of the Hounds that he would not be destroyed from the Flamestrike. This rule therefore prevents players from having to worry too much about complex interactions between doomed minions, as long as they are all destroyed simultaneously.

There is one key difference between Deathrattles and death-related effects: Deathrattles do not activate until the possessing minion has been removed from the board, while for all other death-activated effects, the possessing minion (if any) must still be present on the board in order for the effect to be activated. For example, a Cult Master which dies at the same time as other minions will not trigger from any of the deaths. This is because the Cult Master (and its triggered effect) have already been removed from the board by the time the deaths are resolved, and it therefore cannot be activated by them. Conversely, Deathrattles activate from the death of the possessing minion, and nothing else, and are the only type of effect which remain in play following the death of the possessing minion.

As with all simultaneous effects, it's important to note that Deathrattles and death-related effects occur one at a time, in the order in which the effects were put into play. In the case of Deathrattles, this is determined by the point at which the possessing minion was put into play, or at which the Deathrattle was granted (such as with Ancestral Spirit). For example if a Dark Cultist is summoned followed by a Haunted Creeper, and both are then destroyed at once (with no other friendly minions on the board), the Dark Cultist's Deathrattle will be wasted, since there will be no targets on the board when it activates; while if the Haunted Creeper were summoned first, it would summon Spectral Spiders in time for one of them to gain the Dark Cultist's Deathrattle buff. However, as noted above there is at least one exception: Redemption always activates after the triggering minion's Deathrattle and any death-related effects have played out, regardless of the order in which the effects were put into play.

Another example:


 * 1) A player with a Harvest Golem (summoned first) and a Unstable Ghoul has both minions destroyed at once
 * 2) The Harvest Golem's Deathrattle activates, summoning a Damaged Golem
 * 3) The Unstable Ghoul's Deathrattle activates, dealing 1 damage to all minions, killing the Damaged Golem

If the minions had been played in the opposite order, the Damaged Golem would have been summoned after the Unstable Ghoul's Deathrattle had taken place, allowing it to survive the turn.

A slightly more complex example would be the collision of an injured 5/3 Sylvanas Windrunner into a 3/5 Sludge Belcher. If the Belcher was played first, it will summon its 1/2 Slime before Sylvanas' Deathrattle triggers, giving Sylvanas a chance to steal that minion; whereas if the Sylvanas was played first, it will not get that chance. This can be strategically significant, especially if the opponent has another minion which is far more valuable than the Slime, such as a 6/7 Boulderfist Ogre. Order of summon can ensure that the Ogre is stolen, or can risk the far weaker Slime being taken instead.

Conversely, while Deathrattles and death-related effects take place after minions have been destroyed, they take place before the events which triggered the deaths have resolved. This allows for certain interactions. For example, if a Deathlord is destroyed using a spell, and its Deathrattle puts into play a Wild Pyromancer, the Pyromancer's triggered effect will be triggered from the resolution of the spell. This is because the death process of the Deathlord, including the Deathrattle's summoning of the Pyromancer, takes place within the effect or action phase of the spell; after which the spell than continues its own process, terminating with its resolution phase, which then triggers the Pyromancer.

A step-by-step example:


 * 1) A Harvest Golem is summoned, joining a damaged 2/4 Deathlord, with a Duplicate active (played first of all)
 * 2) The opponent casts Flamestrike, destroying both minions
 * 3) Each of the minions takes damage separately, and are altered visually
 * 4) Both minions are removed from the board simultaneously
 * 5) Consequences of minion death now play out, in the order in which the minions were put into play
 * 6) The Deathlord was summoned first, and its death's consequences therefore play out first
 * 7) The first eligible effect to be put into play is the Duplicate, which copies the Deathlord
 * 8) The next eligible effect to be put into play is the Deathlord's Deathrattle, which puts a Wild Pyromancer onto the opponent's board
 * 9) The Harvest Golem's death is processed next, and its consequences played out
 * 10) The only eligible effect is the Harvest Golem's Deathrattle, which summons a Damaged Golem
 * 11) With the deaths resolved, the Flamestrike cast which caused the deaths resolves
 * 12) The newly-summoned Wild Pyromancer triggers from the spell being resolved, and deals 1 damage to all remaining minions, killing the Damaged Golem

Similar to minion summoning, there appears to be a general check or 'catchup phase' at the end of the phase which triggered the death/s, but before that phase resolves. This allows any effects now in play which would have triggered during an earlier stage of the resolving death/s to be activated. For example, if a Deathlord's Deathrattle puts a Flesheating Ghoul into play for the opponent, the Ghoul's triggered effect will trigger from the death of the Deathlord. This works identically to how a Starving Buzzard will trigger from the summoning of a successfully activated Druid of the Fang, or Unleash the Hounds. For minion summoning this appears to take place at the end of the triggering phase (following the resolution of all involved processes); minion death may be the same, or the catchup phase for minion death may take place after each death. In either case, related effects will activate during the catchup phase despite the fact that they would normally have activated in an earlier phase. However, as explained below, it appears that secrets are not included in the catchup phase.
 * Catchup phase

The consequences of one minion's death may therefore put into play effects which will trigger from either their own death, or that of another simultaneously killed minion. For example, if a Mad Scientist dies at the same moment as another minion, which entered play after the Scientist, and the Scientist puts into play a secret which triggers from minion death (e.g., Duplicate or Redemption) the secret will not trigger from the Scientist's death, but will trigger from the next minion's death. This makes sense, as the secret is activated prior to the other minion's death being resolved. However if a Mad Scientist dies at the same moment as one other minion, which entered play before the Scientist, and the Scientist puts into play a secret which triggers from minion death, the secret will not trigger from either minion's death. Similarly, if a Mad Scientist's Deathrattle puts Duplicate or Redemption into play, the secret will not trigger from the Scientist's death.

The above appears to confirm that while the overall Deathrattle mechanic functions as expected, secrets are not included in the catchup phase; otherwise the death of either the Scientist itself or the minion summoned before it would activate the Duplicate. This is confirmed by the behaviour of Avenge with a lone Sludge Belcher. Regardless of order of play, the Avenge will not trigger from the death of the Sludge Belcher. This appears to be because when Avenge checks for activation, there are no minions on the board, and it thus is not placed in the 'queue' for effects to trigger. However, if it were included in the catchup phase, it would subsequently be triggered due to the presence of the newly-summoned Slime; but this is not the case.

It should be noted that as of February 2015, both the first example of the Mad Scientist's behaviour, and that of the Deathlord/Flesheating Ghoul interaction are being discussed by the devs, and may be changed. However, it is not clear whether this indicates that the behaviour is the result of a bug, or simply that it is unintuitive or undesirable.

Triggered effects and secrets
Triggered effects and secrets have very specific points at which they activate, and this is not always the point at which the event actually took place. Additionally, effects check for activation during the phase in which they would activate, and not at the point at which the triggering event ostensibly occurred.

For example, most triggers related to minion summoning do not trigger from the appearance of the minion on the board, but instead check for activation at specific later stages; in the case of Knife Juggler, after the summoning has resolved. Because of this, using Mind Control Tech to take control of a Knife Juggler will result in the Knife Juggler generating a knife in response to the Mind Control Tech being summoned, even though at the time the Mind Control Tech was summoned, the Knife Juggler belonged to the other player. This is because at the time the Mind Control Tech's summoning resolves, the Knife Juggler is on the same side as the Tech, and is therefore triggered by the resolution of the summoning and thus generates a knife. If the Knife Juggler were instead designed to activate, or check for activation, from the Mind Control Tech's initial summoning (its actual appearance on the board), this would not be possible.

This can cause effects triggered during earlier phases of a process to render an otherwise eligible target ineligible for the purposes of an effect. For example, if a player with two Hobgoblins and a Warsong Commander plays an Argent Squire, the Squire will first trigger each Hobgoblin in turn (in order of play), and its stats will increase to 5/5; as a result, the Warsong Commander will not activate. This is because by the time the Warsong Commander's activation phase is reached, the minion has more than 3 Attack, and thus does not trigger the Warsong's effect. If the Warsong had been queued for activation at the time the Squire was played, it would have activated, despite the Squire having become an ineligible target.

Likewise, effects which activate from minion death only activate once the minion has died and been removed from the board; not at the point at which it is actually dealt fatal damage or destroyed. One consequence of this is that simultaneous effects can restore Health to a minion, preventing it from dying and thus preventing any death-related triggered effects from activating.

Activation phases
Different types of effects activate at different points following the occurrence of the apparent triggering event.


 * Triggers that activate after the triggering event, namely those of Knife Juggler, Wild Pyromancer, Flamewaker and Sword of Justice, trigger after the event has resolved, making them exceptions to the usual rules of thumb for their triggering event types.
 * Minion-summoning triggers usually occur after auras are applied to the minion, but before any Battlecries are activated. However, there are exceptions, for example Murloc Tidecaller activates immediately after the minion is played, and prior to the updating of auras; Knife Juggler and Sword of Justice activate after the event has resolved; and a bug with Warsong Commander means it currently activates after Battlecries. Minion-summoning triggers also appear to be capable of activating at the end of the summoning process, if they were absent during their normal triggering point.
 * Spell-casting and card-playing triggers (except for 'after you cast a spell...' such as Wild Pyromancer) occur after the card has been played, but before it takes effect. In the case of minions this occurs after the minion appears on the board, but before any auras are applied.
 * Spellbender occurs after all other spell-casting triggers have been activated and resolved, but still before the spell takes effect.
 * On-death triggers (including Deathrattles) occur during death resolution, after all dying minions have been removed from the board.
 * On-damage triggers occur after damage is taken, but before consequences such as death are resolved.
 * On-attack triggers occur prior to combat taking place.
 * On-healing triggers occur after healing is received.
 * Start of turn effects take effect at the very start of the player's turn, before any cards have been drawn.

It should be noted that not many cards do not describe the phase in which they take effect. For example, secrets such as Mirror Entity state "when your opponent plays a minion", and yet do not activate from the playing of the minion, but rather after the summoning phase of the minion, specifically following the activation of any Battlecries; meanwhile Hobgoblin, which uses similar phrasing, activates directly after the minion is played, and prior to any other summoning-related effects, including secrets.

Queueing
All relevant effects appear to be ascertained at the start of each phase, and placed in a queue determined by the order in which the cards were originally put into play. Essentially, all relevant triggered effects are triggered at the start of the phase, they simply do not take effect or display their activation until their place in the queue is reached. Note also that effects are checked for activation only once, at the start of the phase. Once the effect's place in the queue is reach, it will be activated.

However, effects which require a specific target will check for their target immediately before activation, and if no valid target is available, will not activate. This prevents effects from 'fizzling' or being wasted. For example, if a hunter plays a Freezing Trap and then an Explosive Trap, an attacking minion will trigger the Freezing Trap first, and be returned to the player's hand, removing it from the board; the Explosive Trap will then trigger, regardless of the fact that there is no longer an attacking minion. This is because both Traps were queued at the start of the phase, while the minion was still on the board. However, if the hunter instead played the Explosive Trap before the Freezing Trap, the minion will first activate the Explosive Trap, and if it is destroyed, will not activate the Freezing Trap. This is because the Freezing Trap requires a specific target, and despite being queued for activation at the start of the phase, checks again for its target before activation.

Another consequence of this system is that minions which are produced by another minion's triggered effect will not activate in response to the activation phase that caused them to be summoned. This is because the minion does not enter play until after the phase has started, and all relevant triggers have already been queued for activation. For example, if Troggzor the Earthinator is destroyed using a spell, his triggered effect will activate, summoning a Burly Rockjaw Trogg, before Troggzor is destroyed. However, the summoned Trogg will not activate in response to the destroying spell being cast. Similarly, is that if during the end of turn phase a Power Overwhelming buff on a Sylvanas Windrunner causes the player to gain control of the opponent's Ragnaros the Firelord, the Ragnaros will not activate, since the phase has already begun. Another example would be that if a friendly Piloted Shredder is destroyed during a player's start of turn phase (such as by a Doomsayer) and it summons another Doomsayer, the new Doomsayer will not activate that turn, despite it being present during the start of turn phase.

Another example would be that an Avenge which is played after a lone Sludge Belcher will not activate from its death, despite the fact that at the point at which the Avenge would have activated, there is a friendly Slime on the board. The reason appears to be that effects check for activation at the trigger point, in this case the resolution of the death of the minion, and not at the moment at which they actually trigger. Otherwise, a Sludge Belcher played before an Avenge would trigger the Avenge for the Slime, since by the time the Avenge would trigger, the Slime would be present on the board. The fact that this doesn't happen shows that the Avenge checks at the point of death/removal of the minion from the board, and not at the actual point at which it would trigger. However, the target for the Avenge will be chosen randomly at the point at which it actually triggers, which appears to show that the Avenge does not actually take action at the start of the phase; it simply becomes 'queued' to activate, with the targeting being part of the secret's action. This behaviour is confirmed by the case of a lone minion dying with a Redemption and an Avenge in play (in that order); despite the Redemption creating a valid target for Avenge, the Avenge still will not trigger, since the board was empty when it checked for queuing.

There is one major exception to this behaviour, apparently exclusive to minions: the 'catchup phase'. This allows any minion effects now in play which would have triggered during an earlier stage of the summoning process to be activated. The phase does not appear to function for spells, since secrets put into play by Mad Scientist appear to be immune to activation in this way. For details on the phase itself, see above. Additionally, effects may still activate in response to the same overall trigger that put them into play if they are triggered by a subsequent phase. For example, as detailed above in the Deathrattles section, if a Fireball destroys a Deathlord, putting a friendly Wild Pyromancer into play, the Pyromancer will be triggered by the Fireball's resolution.

Simultaneous triggered effects
When several triggered effects are activated simultaneously, such as at the beginning or end of a turn, they are essentially considered to take place at the same time. However, each still takes effect one at a time, in the order in which the possessing card was put into play. Following the conclusion of the trigger phase, any deaths are then resolved. This matches the basic sequence of resolution.

As a result, an event will activate all related triggered effects, even if the possessing minions are (or would be) destroyed by other minions' triggered effects before their own are actually shown to activate. This makes it possible for two minions to simultaneously destroy each other as a result of their triggered effects activated by the same event. While the results of their triggered effects may take place one at a time, results are not processed until all triggered effects have taken effect.

Consequently, all triggered effects will always take place prior to the completion of any deaths from triggered effects, and will still occur if the minion possessing the effect is at 0 Health or lower at the point at which the effect is actually activated. For example, this means that a Gruul who was summoned last turn may be hit by Ragnaros the Firelord's triggered effect and survive, as his own triggered effect will then activate, granting him +1 Health, before he can actually die from Ragnaros' damage. Another example would be the use of Shadow Madness in combination with end of turn triggered effects such as Imp Master: if Shadow Madness is cast upon a 1 Health Imp Master, at the end of the turn she will deal herself 1 damage, reducing her to 0 Health, and generate an Imp for the currently controlling player. However, despite being at 0 Health she will not actually die until all end of turn effects have taken place. As a result, she will first swap back to her original owner before then dying on their side of the board, allowing her to trigger effects such as Cult Master for that player and not the other.

As noted above, there are two exceptions to the normal order of events: Poison Seeds and Mimiron's Head, which resolve their triggered deaths immediately in order to make room on the board.

The essence of this rule is that simultaneous triggered effects (such as several "end of turn" effects) are occurring at the same time, but still in a certain order. However, each does take into account the actions of the previous effects to a certain degree. Most critically, while a minion whose Health is reduced to 0 will not actually die until all simultaneous effects have resolved, it will cease to be a valid target for other targeted effects.

For example, if a player has two Knife Jugglers, both of which are activated simultaneously by the summoning of a friendly minion, and the first deals fatal damage to a minion, the second Knife Juggler will not strike that same target, since it has already received fatal damage; despite the fact that the minion has not actually died yet. Likewise, two Ragnaros will not strike the same target at the end of the turn if the first Ragnaros' strike has already dealt it fatal damage. This also applies to non-damaging effects such as that of Blood Imp. If an Imp Master has already reduced its own Health to 0 at the end of the turn, a friendly Blood Imp will not select it as the target for its own end of turn effect, even if this means the Blood Imp's effect is not applied to any minion. However, if the Blood Imp had been summoned before the 1 Health Imp Master, it might grant the Imp Master +1 Health before it could deal damage to itself, thus allowing the Imp Master to survive the turn. Thus order of summoning is once again critical for simultaneously activated effects.

While reaching 0 Health will render a minion no longer a valid target for other targeted effects, it will not prevent it from receiving untargeted or AoE effects such as that of Healing Totem. An Imp Master which reduced itself to 0 Health would still receive +1 Health from a friendly Healing Totem, allowing it to survive the turn.

If the consequences of a previous effect during the same phase results in there being no valid targets remaining for a triggered effect, the effect will still activate, but will have no effect. For example if the first Knife Juggler triggers from the summoning of a minion and deals fatal damage to the only remaining enemy target (the enemy hero), the second will still activate, but will not throw a knife or deal any damage.

An extensive example of simultaneous effects:


 * 1) The player whose turn it currently is has a Baron Geddon, an Acolyte of Pain, a 1-Health Ragnaros the Firelord, a Ysera, and a previously buffed 4/4 Cult Master, summoned in that order, and 9 cards in their hand; the enemy player has only an Ironbark Protector
 * 2) The end of turn phase begins, either by the player clicking 'End Turn', or the turn timer expiring
 * 3) All friendly 'end of turn' triggered effects are triggered
 * 4) Triggered effects begin to activate, in the order in which the minions were summoned
 * 5) Baron Geddon is the first to activate, dealing 2 damage to all other characters
 * 6) Of the minions, the Acolyte of Pain suffers damage first
 * 7) The Acolyte of Pain suffers 2 damage (but is not killed) and draws the owner a card, filling their hand to 10 cards
 * 8) The next target is Ragnaros the Firelord, who was at 1 Health
 * 9) The Ragnaros suffers 2 damage, and becomes marked as dying, but has not yet died
 * 10) Baron Geddon's effect also deals damage to both players, Ysera, the Ironbark Protector and the buffed Cult Master, without consequence
 * 11) Baron Geddon's triggered effect having completed, Ragnaros' triggered effect activates
 * 12) Ragnaros deals 8 damage to a random enemy target, which is determined to be the enemy Ironbark Protector
 * 13) The Ironbark Protector suffers 8 damage, and becomes marked as dying, but has not yet died
 * 14) Ragnaros' triggered effect having completed, Ysera's triggered effect activates
 * 15) Because the Acolyte of Pain already drew the controlling player a card, the player's hand is full, and Ysera therefore cannot generate a Dream Card for them
 * 16) Ysera's triggered effect having completed, all end of turn effects have now taken place
 * 17) The end of turn phase concludes
 * 18) All consequences of the end of turn phase are resolved
 * 19) All fatally damaged minions (in this case Ragnaros and the Ironbark Protector), previously in the 'dying' phase, now die, and are removed from the board
 * 20) The Cult Master triggers from the death of the friendly Ragnaros, and draws a card for its owner; however the player's hand is full and the card is therefore destroyed

Card design
In at least one case, the nature of simultaneous triggered effects has led to specific card design in order to prevent other triggered effects from undoing the card's effect. Mistress of Pain, when used in combination with Auchenai Soulpriest, will repeatedly deal 1 point of damage to the controlling hero, resulting in the immediate death of the hero. However, rather than stop at 0 Health, the Mistress' effect will continue to repeat until the hero has reached -3 Health, at which point it will stop. The card was specifically designed to behave in this way, in order to prevent a simultaneous triggered effect from activating at the same time and healing the hero, thus preventing the player's death.

Rule changes

 * Area of effect healing effects now affect all targets simultaneously, rather than one at a time. Related triggers will still activate one at a time.
 * Secrets can now only activate on your opponent’s turn.

Discussion
The designers have expressed a desire to make the rules of the game more consistent. However, the process appears to be a very gradual one, with changes made due more to necessity than as part of any more comprehensive effort to adjust the rules - at least, thus far. One way rules can change over time is through the addition of new cards which highlight inconsistencies, or otherwise require game mechanics to be altered in order to allow the desired functionality.

Shadowboxer is an excellent example of the invention of a new card causing the game's underlying mechanics to be revised. Prior to the introduction of Shadowboxer, AoE healing effects healed targets one at a time, with any triggered effects activating after each healing occurred. For example, with a Northshire Cleric on the board, a spell like Circle of Healing would heal one minion at a time, with each followed immediately by a card being drawn, before moving on to the next minion. However, this design presented a problem for Shadowboxer's design. The current mechanic at the time of the card's invention meant that with Shadowboxer's triggered effect activated after each healing, and therefore before all healing had taken place, a Circle of Healing would potentially heal the very target the Shadowboxer had just damaged, thus undoing its effects. Likely as a result of the invention of this card, the game mechanic was altered prior to the card's addition, with the result that all single-effect healing now takes place at once, before any related triggers are activated.

While the result was a relatively minor adjustment, it illustrates how the design of future cards might cause standardisation and change to the game's mechanics. Cards which place importance on the results of behaviours which are currently inconsistent, or vary depending on cryptic factors, may cause those mechanics to be adjusted or standardised in order to avoid contradictory results, or in order to facilitate player comprehension and prediction.