Kangaxx the lich?
Only +5 weapons can affect him i think.
I just beated him today.
Thats how i did it:
I killed Firekraag, took the carsomyr + 5. Invited Keldorn in my party, gave him boots of speed, carsomyr. What is very helpfull is to buy protection from magic scroll from adventurer's mart. Buy one, when demi lich shows up get keldorn alone to fight lich (dont forget to cast protection from magic scroll). Now all lich does (only Maze) is useless while you kick his ass.
Easy!

Hope that helps.
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<br />\"Horror has a face,and you must make a friend of horror. Horror - and moral terror - are your friends, if they are not then are enemies to be feared. They are TRULY enemies.\"