The thing that sucks, is that when you are running in WSG, trying to get a flag or stop a flag, the DK can just Death Grip and all your progress is ruined.
Basically, a pull then aggro.
But what is seriously overpowered (in my opinion), is when they death's grip and
Chains of Ice. BUT mages can blink out, druids can travel form, rogues can vanish, and gnomes ftw can Escape Artist (racial) out of it. Oh, and paladins can bubble-hearth.
Why would you go Prot in PvP?
Actually, I've heard that prots are pretty good in PvP. But Fury is much more popular because of titan's grip. Whirlwind with titan's grip can seriously take a chunk of health out of you. It is pretty fricken' hard to melee vs. melee against fury. Unless you stun lock or in my case: kite, jump around, windfury proc, and utilize my totems like crazy.
But I've heard that some prots are f'ing high in dps charts... But people that know their class can still out dps them, because protection is for tanking.
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Anywho. Death's Grip isn't too imbalanced, because many classes have a way of getting out of it. This IS useable while moving. This is NOT useable while falling off a cliff, however. This has a 35 second cooldown, so don't be too afraid of being pulled back immediately. It is supposedly not useable in water.
Don't worry guys, this isn't the top of our "Death Knight OP Abilities List of the Frozen Wastes Jenkins"...