Though a curse effect, Doom is not exclusive to and will stack with other curses cast by the warlock (such as [Curse of Weakness]).
This ability was used by the Pit Lord unit in Warcraft III. It marks a target unit for the manifestation of a Demon. The afflicted unit will take damage per second until it dies. Upon its death, a great Demon will spawn from its corpse.
Patch 9.0.1 (2020-10-13): Now a level 25 talent (was level 30). Damage increased to 175% of spellpower (was 160%), and is dealt after 20 sec (was 30 sec). No longer has a chance to summon a Doomguard.
Patch 8.0.1 (2018-07-17): No longer baseline. Now a level 30 talent. Damage is dealt after 30 seconds, up from 20. Now has a 5% chance to summon a Doomguard.
Patch 4.0.3a (2010-11-23): Damage has been reduced by approximately 12%.
Patch 4.0.1 (2010-10-12): Renamed from Curse of Doom. Redesigned. Now deals damage every 15 seconds for one minute, and has a 20% chance of summoning an Ebon Imp per tick. Cooldown removed. No longer summons a Doomguard. Can now be cast on players.
Patch 3.0.2 (2008-10-14):Curse of Doom will only summon a Doomguard if the target yields experience or honor. The chance of summoning increased to 100%.
Patch 2.0.3 (2007-01-09): Spell power benefit reduced to 200%.
Patch 2.0.1 (2006-12-05): Spell power benefit increased to 400%, up from 100%.
Patch 1.10.0 (2006-03-28): Can no longer be cast on players under control of a creature.