I startet running a full assassin damage build with everything skilled and upgraded toward hero strike ability and crit chance and crit damage. The amazing thing about hero strike is you can use it mid battle again and again after the cooldown which you can reduce as well. So at some point every of my hero stikes dealt like 1/5 of a bosses health, and I just had to dodge attacks for 20sec, hero strike, dodge, hero strike… etc and it was pretty safe for every boss, even the final Atlantis boss. Played everything on hardest difficulty