I'd pop vengeance and IB right before they do that cleave. Also I don't mind opening with a BB-combo on Suparna. Just have BB ready to pull her with, or even flash/tomahawk will do.

Run to your spot. Since you're MT, do a quick Storm's eye combo for extra healing (popping Convalescence too, doesn't hurt). You don't have to worry to lose enmity since no one is attacking them. I use the unchained thingy (unchained, IR, Berserk, BloodB) for some nice extra self-healing.

Plenty of options, but this works for me. Most of the abilities should be ready again when you have the next 'big' pull. What also helps: have your casters toss in Virus and Eye for an Eye for you. People tend to forget about these. They're designed for phases like these, helps a lot!