Friendly Fire says: "Keep all flame legion alive during the defense of the flame citadel" to be able to get a mastery point.
I've tried it a handful of times tonight with groups comprised of dudes who regularly run T4 fractals, who use proper builds including supports, and these NPCs just die too fast. If you were to try and stack more support than 1 or 2, then you have no DPS.
Am I missing some obvious method to complete this achievement? What are we supposed to do here?
And before you ask, YES we were running it with all CMs active.