You have a simple role. Don't waste your time chasing a healer you can't interrupt with any regularity. Instead toss their heals a stun here and there to stop big/crucial heals, and focus the main target. If they go below 50% pop full swing followed by all the burst you have. If they have a whm and the whm is good however afk. You will be slept or bound 95% of the match.