weird, was story stuff normal mode always this easy, or is the weird combo of old ass launch era gear + new gear + new damage/def formulas made my IM a bit broke?
In the lvl 20ish zone and IM regens hp faster than mobs can hurt him. don't even need shield up.
Normal is pretty easy, jump into heroic once you're done or try some other modes out and the difficulty will start to spike a bit.