I downed him my first try on normal difficulty.. paladin / 4x shaman team. I just kept my shammies in a group while my paladin tanks, then use a key to strafe the whole shammy group 5 yards to the side if they get the poison puddle. Arcane barrage, just take the tank to the group, /follow, and keep running in an 'S' pattern until he's about to stop.. park shammies and go back to tanking. As soon as he begins to cast persuit, get your tank back to your group and /follow.. run until persuit is done. Park shammies and tank.. although this is usually when he novas. Luckily, I chain heal topped off right after the persuit and threw down totems (nature resist included), because I was hit with the poison on all 5 characters. The shammies all dropped from ~13.5k hp to ~2.5k, but a quick chain heal got everyone back up quick. The tank went from around 25k hp to 14k, so not a big deal. If I wasn't topped on the shammies, things would have gotten ugly quick! The best advice would probably be to keep running from him AFTER the persuit is over until he stops to cast poison nova.. then you can get safely away to start dps'ing.
The trick to this fight is nature resist, move when you need to move, and burn him down when you can do that too. I threw in a few extra flame shocks while running around when I could, but I'm sure it wouldn't have been a problem to take him down without them.
Connect With Us