Hero Power

A Hero Power is a special ability displayed to the right of each hero's portrait. Usually Hero Powers can be used once per turn and cost 2 mana (or 1 mana for the Demon Hunter), but some effects can modify the mana cost of Hero Powers or allow the use of a Hero Power multiple times per turn.

Each class has its own unique Hero Power, which tends to epitomize its character and playstyle. However, some effects (such as Shadowform or Charged Hammer) are able to replace a Hero Power with a new one, while others modify the rules for some specific Hero Powers.

Hero Powers may have a variety of effects, such as summoning a minion or dealing damage to a target character. Using a Hero Power will activate related triggered effects, most notably friendly Inspire effects.

Overview
The icon for the Hero Power in the game interface is face up when that Hero Power is available to the player, and flips over to a grayish empty space after being used. At the beginning of the player's turn, it flips back up to indicate it is usable once more. Regardless of whether it is face up or down, the Hero Power of the player or the opponent can be hovered over at any time to read its details.

You can not use your Hero Power if:
 * it is flipped over;
 * you cannot pay its mana cost;
 * it would summon a minion but your board is full;
 * it is targeted but there is no valid target.
 * your hero power is Totemic Call and you have all 4 basic totems.
 * Example: Lesser Heal is a targeted Hero Power but, since it does not require a damaged character, it can be used on a full-Health minion too: although having no healing effect, this still counts as a use for Hero Power-related effects.

Usually you can only use each Hero Power once per turn. Your Hero Power flips back up (resetting the "number of times you have used your Hero Power this turn" counter) at the start of your turn and when replaced with a new one: the new Hero Power can thus be used on that same turn if mana allows (even if it is the "same" Hero Power as the replaced one).
 * Example: A hunter could use Steady Shot, trade Majordomo Executus into an enemy minion, then use Ragnaros's replacement Hero Power DIE, INSECT! in a single turn.
 * Example: A player already using the Ragnaros hero could use DIE, INSECT!, sacrifice another Majordomo Executus to become a new copy of Ragnaros with his Hero Power, and then use the "new" DIE, INSECT! once again. With additional copies of Majordomo Executus, this is possible even more times. 

In addition, some effects can refresh a Hero Power, allowing more then one use of it each turn:
 * Coldarra Drake refreshes your Hero Power at Aura Update (Health/Attack) timing.
 * Garrison Commander refreshes your Hero Power at Aura Update (Health/Attack) timing if it was used just once this turn (i.e., if the "number of times you have used your Hero Power this turn" counter is 1).
 * Auctionmaster Beardo refreshes your Hero Power after you cast a spell.
 * Shadowreaper Anduin's Voidform refreshes itself after the player plays a card.
 * Blackwald Pixie refreshes your Hero Power when played.
 * Anraphet's Core refreshes itself after your hero attacks.

Advanced rules
Click 'Expand' to view section

Hero Power Sequence
"Use a Hero Power" is one of the Player Actions that a player can actively do during their turn (the others are: "Play a card", "Attack", "End the turn" and "Concede"), and as such it starts its own Sequence.

To use a Hero Power a player must click on it and, if required, select a target.
 * After clicking on a targeted Hero Power (such as Fireblast and Lesser Heal) a red arrow appears, going from the Hero Power to the player's mouse pointer. It disappears after the player clicks on the chosen target.
 * While Mayor Noggenfogger's effect is active, the red targeting arrow is replaced with a question mark.
 * While choosing a target the player can cancel the action by clicking on the Hero Power again. This is only possible for targeted Hero Powers: Hero Powers that are auto-targeted (such as Steady Shot) or randomly targeted (such as DIE, INSECT!) or that do not require a target at all (such as Reinforce) cannot be undone this way.

Then the following Hero Power Sequence takes place, in order:


 * Hero Power Phase
 * The mana cost of the Hero Power is paid.
 * If the Hero Power requires a target and there is a Mayor Noggenfogger in play since the last Aura Update (Other) Step, its effect triggers and randomly selects a valid target; multiple Mayor Noggenfoggers stack.
 * The Hero Power takes effect.
 * The Hero Power is exhausted and flipped over (the Hero Power visually seems to flip over before Mayor Noggenfogger triggers, but in the log file it is exhausted after having taken effect).
 * The "number of times you have used your Hero Power this turn" and the "number of times you have used a Hero Power this game" counters are increased by 1.
 * The "number of times you have used your Hero Power this turn" counter is reset at the start of your turn and whenever your Hero Power is replaced with a new one.
 * The "number of times you have used a Hero Power this game" counter (which is for example used for the cost reduction of Frost Giant) never resets, regardless of your Hero Power being replaced, upgraded or otherwise modified.


 * Inspire Phase
 * Hero Power-related triggers (listed in the following table) queue and resolve. Most of them have the Inspire keyword, which denotes triggered effects that activate each time the controlling player uses a Hero Power.


 * Hearthstone checks for win/loss/draw.

Player Hero Powers
Players start each match with the basic Hero Power of their class (sometimes also referred to as that class' starting Hero Power).
 * Alternate heroes use cosmetically altered versions of the basic Hero Powers: although there is no functional difference, the appearance and casting animations vary from those used by the standard heroes.

Over the course of the match certain effects can replace a player's Hero Power with another one, regardless of that player's class or hero:
 * Renounce Darkness replaces your current Hero Power with the basic Hero Power of a random non-warlock class.
 * Sir Finley Mrrgglton lets you Discover another basic Hero Power. More precisely, this minion's Battlecry forces you to replace your Hero Power with one among three randomly selected basic Hero Powers, with the exception of the basic Hero Power corresponding to your current Hero Power's class (see the table below).
 * Example: If you are a priest with the Mind Spike Hero Power, Sir Finley Mrrgglton's Battlecry can not offer you Lesser Heal (since it is the basic Hero Power of the Mind Spike's class), but it can still offer you the mage basic Hero Power Fireblast.


 * Justicar Trueheart and Baku the Mooneater replaces a basic Hero Power with the corresponding upgraded Hero Power (see the table below). It will have no effect if you don't have one of the 10 basic Hero Powers.
 * Sir Finley of the Sands allows you to access the same upgraded Hero Powers, but can select any instead of directly replacing.
 * Hero cards replace your current Hero Power with the Hero Card Hero Power of the appropriate class.
 * Other effects (Dinomancy, Vilefin Inquisitor, Shadowform, Charged Hammer, Sulfuras, Lord Jaraxxus, Majordomo Executus, Metamorphosis) replace your current Hero Power with a specific alternative Hero Power.
 * If your Hero Power is not Mind Shatter nor Mind Spike, Shadowform will replace it with Mind Spike.
 * If your Hero Power is already Mind Spike, Shadowform will replace it with Mind Shatter.
 * If your Hero Power is already Mind Shatter, Shadowform will have no effect (including not refreshing your Hero Power).


 * Sideshow Spelleater replaces your current Hero Power with a copy of the opponent's current Hero Power (whatever it is).
 * Grizzled Wizard swaps hero powers of both players, then swaps them back on the following turn.
 * The Quest cards introduced in Saviors of Uldum provide an alternate Hero Power which replaces your current one immediately upon being completed.

 Click 'Expand' to view all Hero Powers in play mode 

Related cards
The following cards generate, modify, respond to or otherwise relate to Hero Powers and their use.

Boss Hero Powers
Most non-playable bosses have their own Hero Power. Adventure bosses have both Normal and Heroic versions, with the latter usually featuring enhanced versions of their Hero Powers. Some bosses gain different Hero Powers over the course of the encounter due to cards or the Hero Powers themselves.

Boss Hero Powers vary in cost and may cost anywhere from 0 to 8 mana. Some boss Hero Powers are "auto-cast" automatically as the boss's first action each turn, assuming it has enough mana. This means that the boss is not able to choose the best time to make use of the Hero Power, or to forgo using it on any given turn. Auto-cast Hero Powers have a special ongoing visual effect. Typically auto-cast Hero Powers are cheap, including the majority of those that cost 0 mana. Other boss Hero Powers are passive, causing a free ongoing or triggered effect rather than being used at one particular time.

For full lists of boss Hero Powers, see Boss card.


 * Examples

Strategy
Available each and every turn, Hero Powers can allow players to gain card advantage by taking actions without expending cards. Players can choose to use a Hero Power instead of playing a card, sacrificing some tempo in exchange for a larger hand. Hero Powers can also be used often in order to keep pace while holding back cards to build toward a combo, or to fill gaps when no other strong play is available. Hero Powers should generally be used whenever there is sufficient spare mana.

Basic Hero Powers are designed to offer a reliable but underpowered effect. For almost all basic Hero Powers, it is possible to identify cards that accomplish more for less mana, and cards that do significantly more for 2-3 mana. This mana inefficiency prevents Hero Powers from being directly superior to cards in most cases, making them reliable secondary options rather than first choices each turn. Generally speaking, Hero Powers are effects at the value of a 0-Cost card, as evident by comparing the paladin Hero Power Reinforce with the minion card Wisp, or the mage Hero Power Fireblast with the spell card Moonfire. The extra 2 mana is effectively a surcharge for gaining the effect without consuming a card.

Here are some examples for illustration:

Note that the Totemic Call's randomness itself also makes the Hero Power comparatively weaker than a well-chosen equivalent in the hand. Still, each Totem other than Healing Totem can be compared unfavorably to cards, just as with other Powers: Healing Totem's effect is unique so it cannot be said to be strictly worse than examples like the Darkscale Healer or Lightwell. But again, due to the randomness of Totemic Call and situational usefulness of the summoned Totems, it is clear that it shares other basic Hero Powers' weaknesses with respect to tempo.

History
Hearthstone has included the basic Hero Powers for its nine classes since the very beginning. Although these "starting Hero Powers" have not changed, the variety and availability of Hero Power-related effects has increased over the years, including effects that replace the starting Hero Powers completely.

The Classic set included the priest's Auchenai Soulpriest, Shadowform and Prophet Velen, as well as the warlock's Lord Jaraxxus - two cards that replaced Hero Powers, and two cards that affected all healing and/or damage effects including Hero Powers, all class-specific. Steamwheedle Sniper in Goblins vs Gnomes introduced the first dramatic change to the way an existing Hero Power worked, although again it was limited to one class and its Hero Powers. Blackrock Mountain 's Majordomo Executus provided the first neutral Hero Power-related card, with an effect very similar to Lord Jaraxxus'.

The Grand Tournament expansion had a particular focus on Hero Powers, increasing the number of Hero-Power related cards by a factor of 6 with a multitude of effects and interactions, most notably the Inspire ability. Since then, adventures and expansions have slowly continued expanding on Hero Powers with 2 cards from The League of Explorers, 3 from Whispers of the Old Gods, 2 from Mean Streets of Gadgetzan, 2 from Journey to Un'Goro, and one for each class in Knights of the Frozen Throne via Hero cards.

Blizzard has consistently introduced new effects that replace Hero Powers through new card sets, with almost half of Hero Power-related cards outside of The Grand Tournament including such effects. On the other hand, Inspire has not been on any cards since the expansion in which it was introduced.

Gallery

 * Frames