Requirements: must land killing blow in order for the boss to count
Mar 10 2011: Landing killing blow was not required to get the mark. Getting boss credit for the kill may be required.
Kill 66 distinct bosses.
Refer to this Boss List to locate NPCs that will count towards this mark.
Bosses seem to have individual level or class requirements based on the level of that NPC. Please help us gather facts about which bosses counted for your current level/class. Thanks!