Took me a few attempts, but got it eventually.
I kept getting hit with some crazy ability he would use that would kill me instantly at 50% health, but managed to use Pacify to deal with that.
I'm a Watchamn spec'ed Sentinel with Surge/Crit equipment. Didn't even really need T7 either.
*shrug*
The one issue I DID have was the disappearing act that he would pull after I would die and after I was finally victorious. Kinda annoying, but fixed after a 5 minute wait.