From release to now, I have never had Scourge Sacrifice casted on me.
It's quite possibly the worst skill in the game. They should make it more than twice, so that a necro that doesn't notice its on him would be dead in 2-3 casts. But then again that's just like backfire, except only works for sacrifice skills. So imo it should be even more damage than that.
Its the kind of skill that makes a lot of difference when its there but when its not needed its a waste of a slot. If i run warrior train and am smiting then slap it on the smiter, the utility > damage. Bip, etc all take a beating.