Alright, I can understand the concept of NOT doing an alignment shift each time you use an evil spell. "Hey, I'm LG, and I want to be a Red Wizard/Pale Master... etc, I'll just cast this spell a bunch of times and Wham! Yeah, goal accomplished and no need for any DM intervention"
HOWEVER,
... perhaps we could consider a cap on the amount of evil required to cast one of these spells (I'm looking at you Abyssal Might and Summon Nightmare!), so that otherwise semi decent (read mostly Neutral) casters can't just use them willy nilly without some long and deliberate thought and action (like eating little babies and spanking paladins for fun).
HOWEVER,

Comment