Bosses are a type of mob that are found in instances, raid areas, and capital cities. They have unique names (only one mob with that name) and are designed to be higher in difficulty than a normal or elite mob, sometimes with powerful spells or special abilities, almost always with a level and hitpoint rating disproportionately large in comparison with the other mobs in the instance or surrounding area. There are also "skull bosses", for which you can't see the level (see below). An instance may contain several bosses, some of which may be optional, with a higher-difficulty boss at the end. Boss mobs are generally immune to crowd control and may have immunities to select magic schools.
Boss mobs are the primary source of rare and epic items in the game and, for this reason, are generally the motivating factor for completing instances.
Instance
Examples of instance-end bosses:
- Edwin VanCleef (Deadmines boss)
- Mekgineer Thermaplugg (Gnomeregan boss)
- Archmage Arugal (Shadowfang Keep boss)
- Lord Pythas (Wailing Caverns boss)
- Amnennar the Coldbringer (Razorfen Downs boss)
Examples of "skull bosses"
- Ragnaros (Molten Core boss)
- Nefarian (Blackwing Lair boss)
- Hakkar the Soulflayer (Zul'Gurub boss)
- C'Thun (Ahn'Qiraj boss)
As of the Burning Crusade expansion, Vanndar Stormpike and Drek'thar of Alterac Valley are also bosses.
City
Faction leaders are located in each faction's capital cities, and are also classified as bosses.
Examples of faction leaders:
Outdoor
Other bosses exist in raid areas throughout Azeroth and Outland, such as Doom Lord Kazzak and the Emerald Dragons. These bosses will spawn infrequently, and are the source of much competition, as they spawn in the non-instanced world.
Resist and crushing blows
Miscellaneous Info
It was confirmed by Blizzard employees that all bosses were considered as three levels higher than the player attacking them, whatever the actual level of that player [1]. That is, if both a 60th level warrior and a 65-level druid attack a world boss in Naxxramas (for instance), the creature will make crushing blows on the warrior as if it was 63, and on the druid as if it was 68. Similarly, the boss will resist their respective powers as a 63- and 68-level creature would.
This only applies to the ability to make crushing blow and to resist spells. Whatever the level of the raid, the boss' HP, armor and damages are unchanged. Remember, though, that a given score in spell critical hit/armor class/whatever is less and less effective when you gain levels, so a world boss can actually strike harder on a 62-level tank than on a 60- if they have the same gear.
See also: Mini-Boss