Uber bosses are tough. I'm fairly well geared and can solo all mp10 bosses without a problem. However, i can't beat uber sk/magda or uber kulle/seige. When seige picks me up, kulle's tornado and rocks can hurt me. Ghom/rakanoth at mp10 was easy though. I might go around beating sk/magda when i get some 200 extra All Resist to survive 3 stacking butterflies. I have no idea how to solo kulle/seige.
