I tried him today, failed, but I know I could have had him. I got him down to 17%.
My mistakes:
#1) Merc didn't have a C and went oom, and C9 would have worked. She CH'd herself at the end instead of me, I was ready to fire her.
#2) I took on a named on the fly. I never raided here, so I didn't know until after I started the fight that he has over 350K hp.
#3) Not having any Quellious poisons, I couldn't divert agro to the merc so that I could use my backstabs. Triple backstab, Blade of Nightmares and Ragebringer.
On the good side, I have 400+ aa's, working on Virulent Venom rk5, to increase poison procs. And with the new poison system, I was hitting for 3002 dmg often, and critting for 6004.
Just don't flame me for not being r33t.