Thorim's arena phase got buffed significantly (either on tuesday or through a hotfix) and is now much more annoying o.O
Some of the adds now cast a shield which absorbs 120k magic dmg (on 25man) and reduces physical dmg done to them by 50%.
(Other adds now have an aura which increases haste by 20% which is less annoying but still significant)
It would have been nice to have known about these buffs before starting to deal with him tonight >.<