Run their stampool out of resources. Spam light attacks, fear, shades( dual shades), cripple, incap strike, soul tether etc will force them to break CC with their stamina pool. Sorry but I disagree completely with nerfing anyone based on who you can't kill right now. Those perma-block builds sure... they are annoying but only because you're trying to kill them. They should be ignored and zerged down after the DPS and heals are dead.