Vael: You caught me, those were added after I thought up the original idea, because I wanted a PrC with more than 4 abilities.
So, I nixed the truth abilities and shrunk it down to a 5-level PrC, and I upped the Knowledge requirements. Clerics only get 2 skill points a level, they wouldn't be able to get into the thing until level 10 or so. Is it really that overpowered?
EDIT: Huh, forgot about Cloistered Cleric variant. Guess it will need some feat or something to gain entry after all.