Odd. I wasn't that strong and I only had minimal trouble with the final boss. Were you trying to dive bomb him with multiple characters by any chance?
You can't do that. His Evility allows him to steal stats, per character, for every step you walk in his AoE range.
So basically unless you're utilizing range or 1v1-ing (with a healer outside of stealing range) you're giving him huge
surges of power per turn. If you avoid proc'ing his Evility then he's rather soft for a final boss.
Yes I quite aware of all that... I tried various strategies, including being cheap and lifting him each turn and still got dwarfed. My new strategy is reincarnate, re-grind my characters in the item world and eventually out-cheap-ify the bastard. If you can't beat the game, break the game right? LoL