Originally Posted by
sdream
Ah CODzilla.
Extra spells, infinite spellbook, no arcane spell failure, heavy armor, lots of skill points, rogue BAB, better than rogue hp, spontaneous casting and other powerful class perks.
Start just by making them use a prayerbook, just like a spellbook.
Follow up by applying spell failure if they wear heavy armor, just like mages.
Drop their base HP and BAB to wizard/sorcerer levels
If they give you a hard time, remind them that they have been focusing on praying powerful prayers, not fighting. Offer them the paladin class if they want a holy warrior with some spellcasting.
Full spellcasters give UP physical power for magical power, they don't get both.
Half casters (see ranger, paladin, bard, warlock etc) get some physical power and some magical power.