Corrupt Spell( Complete Divine, p. 79)
You can transform one of your spells into an evil version of itself.
Any evil alignment,
This feat adds the evil descriptor to a spell. Furthermore, if the spell deals damage, half of the damage (rounded down) results directly from divine power and is therefore not subject to be reduced by resistance or immunity to energy-based attacks. The corrupted spell uses up a spell slot one level higher than the spell's actual level.