Necropolis or Castle (Which one is stronger?)

Quote from Black Mage:

Don't cast Blessing on peasants! Actually... don't cast Curse either... And in general, why do you even need them?

I can't resist commenting :) . Blessing at the advanced and expert levels on peasants doubles their damage, while Curse really doesn't do anything.
P.S. And in general, why do I even need them? :D .