I tried this a bunch today as scoundrel (full sawbones tree *_* lol) and got my *** kicked a few times. But then decided to sacrifice corso (sorry buddy!) and then pretty much played peek-a-boo the whole time behind one of the big pillars and do nothing but throw thermal grenades after phase 1. Phase 1: straight tank with corso, only needed kolto cloud + 2stack of emergency medpack to keep him alive Phase 2: peek a boo!, throwing thermal grenades like a muppet. Arho will chase you around the pillar so you can keep running in circles, turn to face him and toss a charge at him. Flash grenade works if you think he's getting too close for comfort and you need to get a few seconds break. Phase 3: hug that pillar! (no, really!) if you LoS and sick right on it, you don't take damage from the huge storm, so duck out, toss a grenade and keep kolto cloud on to recover any hp you might lose (I didn't dip below 95% in this phase) Long fight, maybe like 5~10min? but it was fun!