Paladin was probably more due to being absurdly overpowered than anything.
To be fair, on any level except Hex Ruins the paladin is even more
overpowered now, and he's never been particularly well-suited to most vicious levels (though he absolutely dominates most hard-difficulty levels).
How bout' the priest cannot lose piety and 100% undead damage...
Yeah that's much too powerful.
Not sure if half piety loss would be very helpful. You're either worshipping a piety farm and can afford the hit, or you're worshipping a stingy miser like GG or Dracul and you really can't afford to give up ANY piety anyways.