Ha, another weak enemy for the true mage. I was level 26 when I defeated him, and I must say, it was simple.
Just get about 100 magic potions for the dungeon. Make sure you have either the Lightening spell or the Meteorstrike spell at at least 3 level. Also, a good idea is to have Limbs of Lead, or Burning Wall. Each one can be used to slow him down while you pummel him with meteors, spikes, or electricity.
Using -just- meteorstrike and limbs of lead I took out every single orc in the east <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />, starting at level 16 <img src="/ubbthreads/images/graemlins/alien.gif" alt="" />.