Originally Posted by Saint of Killers
Improved Mace of Destruction counts as a +5 weapon. It'll hit every enemy in the game. Protection from Undead will make any lich ignore you, so you can kill them in peace.
I'm not sure which lich you're talking about, though. If it's Kangaxx, all you have to do is have everyone but your mage read a Protection from Undead scroll, then have your mage cast Protection from Magic: Abjuration so he can't be imprisoned. When Kangaxx's near dead you have to have your mage (who was safely waiting off screen up until this point) talk to him (which is why he didn't read a scroll, because if he did Kangaxx would ignore him) so he turns into a demilich. Whoever's carrying the Improved Mace and maybe Carsomyr if you have a Paladin then turns him into a fine paste.
If it's Shangalar, that fight's alot tougher. But only because he hangs around a bunch of nasty non-undead types.