I faced him the first time with a pure melee hero and couldn't do much damage at all - sooner or later I was going to run out of potions and die.
While fighting I paused and I unlearned one skill so I could learn hammer. My intelligence was awful but I was able to cast it once with my mana pool (note that if you can't potions of intelligence or charms/items of mana/intelligence will allow you to). Fortunately I am a pack rat - had over 80 mana potions.
So I cast hammer, took mana potion - swung twice; cast hammer, took mana potion - swung twice; repeat as needed. Note that the hammer paralysis gives you time to get behind him to benefit from backstab if you have that skill. I didn't.
Took some time but after learning hammer even at level 1 I was never at risk.
