Each boss presents a unique encounter, featuring their own Hero Power and decks. Bosses use a combination of regular cards and boss cards, special and often extremely powerful cards available only within specific encounters. Bosses can be encountered in Normal or Heroic mode, and defeating a Heroic boss usually presents quite a challenge, with players needing to devise special decks to counter the mechanics of that specific fight.
Bosses usually represent well-known characters from Warcraft lore, with their Hero Powers and cards in keeping with their personalities. Boss battles also feature dialogue, involving the boss as well as other characters.
Boss battles use the same general framework as regular matches, but have specific differences separating them from normal gameplay, ranging from a few special cards with additional flavor, to complete transformation of some of the normal game mechanics.
Boss battles are generally designed to offer a specific challenge, usually featuring a strong theme or style, forcing the player to find a way to defeat them. Players often must alter their decks or construct new ones in order to beat specific bosses, with each having its own strengths and weaknesses.
Boss encounters may feature multiple phases. In these battles, specific events will trigger transition into the next phase, usually accompanied by special dialogue, and resulting in the boss gaining a new Hero Power, new minions on the board, and/or adjustments to Health or Armor.
Similarly, while most boss encounters feature only one boss, some feature more, with specific events (usually the defeat of the current boss) causing them to be replaced by a new one. In this case all bosses must be defeated in order to complete the encounter.
Certain boss encounters feature special limitations, such as the Heroic Loatheb encounter, during which it is not permitted to use Alexstrasza. These limitations are not announced, but attempting to use the restricted cards during the encounter will see the minion or spell destroyed or countered, with no mana refund offered, accompanied by a little gloating from the adventure's host. Curse of Naxxramas features several such restrictions, while Blackrock Mountain has none.
Each boss encounter features its own dialogue, which may involve the boss as well as other characters. Bosses have a number of quotes which are elicited by certain events, such as the start of the battle, the use of a certain card, player emotes, or the defeat of the boss. For a list of boss dialogue, see individual boss pages, e.g., Noth the Plaguebringer.
Normal and Heroic
Bosses found in adventures can be fought in Normal or Heroic mode. Heroic mode bosses usually feature more powerful Hero Powers, as well as more Health. They may also use slightly different decks, as well as improved versions of boss cards.
While Normal mode bosses typically offer minimal resistance, Heroic mode bosses are designed to provide a substantial challenge. Heroic bosses usually require several attempts to defeat by even experienced players, and generally require the construction of new and specific decks in order to counter the boss' unique abilities and style. Heroic bosses are therefore designed to offer a challenge not only in play, but in deck construction.
Each boss features a unique selection of cards. Bosses may use regular collectible cards, but also have access to unique boss cards, special and often extremely powerful cards which are not available to players. Bosses themselves do not belong to classes, but may use cards belonging to any class, as well as neutral cards. This can produce some interesting card combinations, such as Hunter's Mark and Mortal Coil. Boss decks may feature more than 30 cards in total, and like Arena decks are not subject to the 2-copies-per-card limit found in constructed play, sometimes featuring as many as 10 copies of the same card.
The lack of boss class is significant for class-related effects like Nefarian, Burgle and Swashburglar: when played against bosses these effects will instead generate copies of specific cards. Most generate The Coin, but Nefarian usually generates Tail Swipe instead.
Boss Hero Powers vary in cost, and like boss cards often feature very powerful effects for a very small amount of mana.
Some boss Hero Powers are auto-cast, indicated by a special ongoing visual effect around the Hero Power on the battlefield. Auto-cast boss Hero Powers are activated automatically at the start of the boss' turn when possible, following any 'start of turn' triggered effects. 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. However, there are some exceptions, such as Brood Affliction, which is auto-cast but specifically activates at the end of the turn. Auto-cast boss Hero Powers usually have a mana cost of 0, but may cost more.
Tutorial bosses are slightly different from adventure bosses. As the fights are very specifically scripted, it is assumed these heroes do not have full decks, but rather a small selection of cards, which are always drawn in the same order. Not all tutorial bosses have Hero Powers.
Tavern Brawl bosses
Some Tavern Brawls feature bosses of one kind or another:
- Single-player Brawls like Storming Stormwind are very similar to regular boss encounters, albeit often with special twists specific to the Brawl.
- Cooperative Tavern Brawls like Nefarian Rises! feature a special boss minion, which moves from one side of the board to the other each turn, with the objective of the Brawl being to defeat it by working together with the other player.
- Main article: Boss card
Boss cards are special cards used by bosses, and are not available to players. Boss cards may be unique to a single boss, or be used by several.
Free from the constraints of the balancing required for playable cards, boss cards often feature outlandish powers and effects.
- While a number of bosses are also featured as playable minion cards, there is no functional connection between the heroes and the minion cards. Currently 5 of the 6 tutorial bosses feature as minion cards (with the sixth's minion card having since been replaced), along with 4 of the 15 Curse of Naxxramas bosses, 7 of the 20 Blackrock Mountain bosses (including sub-bosses), 3 of the 13 The League of Explorers bosses (although 2 of those are in slightly altered form), 5 of the 17 One Night in Karazhan bosses and 4 of 9 Knights of the Frozen Throne bosses.