This man speaks the truth. I generally never see my health pool move in phase2 unless i'm doing something stupid.
http://i.imgur.com/audRhQE.jpg
Pick them up with shieldwall, after that - bam, no damage taken. (And highest damage done!).
I don't even think I took damage equal to my health pool in Phase2 this week.
As for the OP, I never stun the adds, seeing as they can't actually hit me, it's kinda pointless.
Our other tank does stun adds/get his adds stunned for him and he occasionally gets wrecked by sonic blade.