I removed the onSpawn script (the one that gives him the force shield effect), but I think that messes up something with his user define script when he dies.
There is another instance that I got locked in the tomb however - I placed a lot of mines in his area right before the fight and it instantly killed him...
...but also I think I killed him too good because I got XP points and he didn't disappear. And I think that must mess up the door unlock script.