Soul Drain

[Cor2]

Soul drain does a tiny amount of damage, so if your expecting it to stop an army it wont for at least 6-7 rounds. What it will do is reinvigerate the caster every round, so prepare some other nasty spells.

I have not seen the code but my guess is that its damage is the drian life effect, so it will hurt undead too but you won't get the life from them.