Okey I have serach and didnt find any thread about this.
But I have done DTK on my shaman a few times this week and I as u all now so can u bubble, vanish and iceblock the spell he cast so u turn into a skeleton.
Well I wanted to try if u run back down the stairs after you have started the combat and see if he casted the spell on you or if he didnt.
It worked as I thougt and he do NOT turn you in to a skeleton, so u can just run up and keep dpsing while the rest of the party are skeletons. I have try this on my druid and shaman and it should work for any class if u dont got aggro from the boss so he follows you.
Sry for my bad grammer but I hope u understand