[Baalz]

If you mean does the extra affliction chance (the only part of the death bless which effects spells) apply when you damage your own troops, yes it does. Given the difficulty to use effectively (holy mages powerful enough to cast battlefield wide spells are moderately rare) and opportunity cost (you could have a water or fire bless) I certainly don't think the death bless is overpowered. A nice bonus, yes, but you're unlikely to win a war because of it.