You must've had a bad day or something cause shadow is a blast.

Devouring plague talented almost 1 shots people... followed by 4 shadow word deaths = instant kills.

Only thing is they arent for killing large numbers of mobs like druids/shamans. But get about 4 -6 people you can just run around dotting people and never dieing. With the mana fix I hardly ever run out of mana like i used to.