Death Knights, seriously, I went to Honor Hold (HFP, ya know ;D) Took down Danath Trollbane, went out, and it took a 80 Rogue and a 80 Pala to get me down finally, gotta love a blood tank dk <3.
Secondly I must say a warlock, purely for the whole evil thing that surrounds them ^.^ .
Secondly I must say a warlock, purely for the whole evil thing that surrounds them ^.^ .