This morning at 7am(et). When I was raiding a person their normal hits were giving out over 300 damage per hit to my heroes. This started to happen mid way through the raid. No debuffs were on my heroes at this time. One normal hit knocked out a heroom that had full health. I have fully ascended 4*'s and was facing almost fully ascended 4*s.
Do you remember who the other team had?
Sounds like you got Wu Konged.