Raise Dead is a death knight ability learned at level 56. It allows the death knight to raise a Risen Ghoul to fight for a limited time. This creature can perform a number of attacks including fear, apply disease, stun, cause a target bleed, and pummel.
With Master of Ghouls (Unholy specialization), the ghoul becomes a permanent pet under the death knight's control.
Even if you aren't Unholy specced, don't forget that Raise Dead is still a DPS cooldown!
Patch 3.3.3 (2010-03-23): It is no longer possible when this ability is used in conjunction with temporary pets from quests for the ability to get permanently stuck on cooldown.
Patch 3.3.0 (08-Dec-2009): It is no longer possible under some circumstances to use a Risen Ghoul to cause neutral guards to attack opposite faction players.
Patch 3.2.0 (04-Aug-2009): This spell will no longer give two errors when the casting player lacks the reagent to cast it.
Patch 3.1.0 (14-Apr-2009): Duration lowered to 60 sec. and cooldown lowered to 3 min. The cooldown on this ability now begins when the pet dies rather than when it is summoned. This pet now despawns instantly when it dies. In addition, this ability can no longer be used while riding any type of vehicle. The Risen Ghoul is also now properly immune to Charm, Fear, Sleep, and Horror.
Patch 3.0.8 (2009-01-20): Raise Dead has now been split into two spells:
Raise Dead now raises a ghoul or pet ghoul (if talented). Requires [Corpse Dust] if no humanoid corpse is nearby.
Raise Ally now raises a fallen party member and has no reagent. Available at level 72.