Pandasaur, i agree, it sucks. But you can cheese the fight. You just have to have a char with more init then the doctor in human form and simply disable (stun/sleep/whatever) him until you kill him. You probably miss a lot of exp that way (the 4 demon adds don't spawn, i assume the candle quest gives exp also at the end) but atleast one can continue.
But all of it doesn't matter since the final quest is bugged anyway.
