Thought bubbles hit you with "Escape" aoe, that should obviously be avoided. There's still Grim Wound, Earth Destruction, and Dark Infirmament or w/e (first two seems to be casted by adds and last casted by Sismond) that hit ridiculously hard on percentage level. Not sure how to avoid that or if the adds even play a part to the fight, and we still don't know the reason behind the disparity in nuymber of rounds.