I killed him at level 22ish with this tactic:
Mage - curse1, freeze4, elemental arrow x 10ish, freeze4, elemental arrow x 10ish ... dead.
The reward is kinda stupid, some pole axe that I sold.
The dialog box makes it hard to get your action in before he hits you, so I started off with healing myself even before it looked like I needed too, but the timing ended up being right.
Calonderiel
