I have not done the complete main quest, but do you battle him more times than 1?
Cause I defeted him now when I went in the mind place thingiemajingie.
and he did not use any kind of heal and the orbs did almost no dmg. I am lvl 15 on this character.
I stopped doign dmg to him from time to time to see if he did anything except teleporting and summon some orbs that died in 2 light attacks.
Maybe you get some kind of bug? or what happends when you die?