Originally Posted by
Skarssen
Certain abilities can be very useful on multiple encounters;
1) death grip (heroic Malkorok, Sha, etc). Not a NECESSITY, but very useful and can significantly ease certain encounters
2) Gorefiends Grasp. Similar to DG in its unique advantages
3) AMZ. Few encounters can take advantage since it requires the raid to stack up, but can be a big bonus when applicable.
4) Very good burst AOE with frost, decent sustained AOE with unholy
To be honest, other than the 2 grip mechanics we don't have anything that is indispensable, and we don't have the damage reduction CDs of a rogue, warlock or shadow priest. Our damage output is okay, but worse than rogue and warrior. Unfortunately both rogues and warriors bring equally useful raid abilities such as smokebomb, Cloak of Shadows soaking (Malkorok orbs, etc), Demo/Skull banner, rallying cry, vigilance, intervene, etc. Of course ranged DPS would be better, but if you are looking for a melee and already have a rogue and warrior a DPS DK can be useful, but outside of the grips (and if you have a blood tank a second set of grips isn't all that userful, unlike warrior banners) I think you could probably do without one.