GO LEARN YOUR INTERUPT ABILITIES!!!!!
As an inquisitor I can say that he does dangerous stuff at roughly twice the speed that my only interrupt (that can affect him) recharges. Try again.
The best solution to this quest is to bring a friend. Thats it. I do like hard stuff sometimes, but this quest should be labeled 2+.
ps. Ive been level 50 for weeks, but I do remember that this quest made me stop. I ran into only two bosses that I couldnt solo, avatar was one of them.