As a tank if you’re getting circled around and cant seem to hit the barbarian, you can simply back up to a wall. If you can hit em then give them no quarter. Keep incessantly attacking and give them no breathing room. If you let them step in and out whenever they please you will be in trouble. If you got CC use them. Anything you can do to stop their movement is always good.

For casters. Try to keep the distance and CC them before they CC you. This is the only way to survive the starter combination of a berserker really. If you by some miracle survive it then do whatever you can, CC, DD, run away or whatever else you see fit. You will have about til your stun and knock back immunities wear off and they can do it all over again.