Killed him with tank speccing dps.
setup:
Operative - healer (me)
Mercenary - dps
Juggernaut - dps
Juggernaut - dps (tank gear)
Tank got one shot and again after combat ress but he had only 14.5k hp.
Healing gets harder at the end, at the beginning i was able to do some dps.
You can use your anti movement impairing spell on the cc he casts on random player, the lifting thing.