I'm playing on normal and my poor paladin sweated blood and tears to hit 20 - had one look at the Korador fight and said no way can he make it.
MY mage, well he's basically laughed his way to the same point, once you get fire rain - mine took some time to come, mobs just die
Hypnosis+sacrifice is the cheesiest combo ever - not to say I haven't been abusing it
MY favourite army is currently, evil beholders (for wasting the melee mobs turn), dryads and succubi for the charm and all I have to do is wait with the sacrifice.
I want to finish this game and then start a new paladin, definitely a harder game to play then the mage.
Don't think chaos is really necessary for the pally, unless he can reach really high int levels and he will struggle to have enough magic runes, even with runic stone. Better off with effect based spells from distortion like haste(mass), stone skin, trap for the ap loss even berserk is great on the royal snakes.