[Xyndra]

I don't have CoE. You could do a few things depending on level and how much of a beating you can take. What I do is dot every one of them with Siphon Life, Corruption, Curse of Agony. Once they are all dotted, I could use howl of terror, then drain-life each of them while feared.

You could also send in the VoidWalker to collect all four mobs and dot each of them with the dots above, then just pick one and drain away.

I've never used Curse of Exhaustion. I don't pvp much and use fear for getting mobs off me.

But that's just me.