After about 50 attempts and a hell of a lot of coffee/willpower, I finally defeated him as a lvl 46 marauder. That guy is relentless!
Wouldent advise taking him head on, cd's dont refresh quick enough and after a short while he'll just nuke you to bits, ended up just running in with Charge, battered him a few times, sent Jaesa in my place and kited him around the pillars, getting a few shots in when neccesary and just generally getting a few DoT's on him. It'll take a while but it worked for me. The key is not to get caught up in his storm ability and his immobilising ability which shouldnt be too hard providing you kite him.
Good luck! I hated this guy