This boss is SO easy, it really is all on the healer, you have to dispel his DoT when it gets put on someone or else they will take a crap load of damage, other then that, dodging the fireballs is easymode.
unfortunately bodyguards don't get cure until level 24
But yes, the trick is to realize you can run in circles around the statue at the top of the stairs. However, the trick for the healer is to top everyone off, and start the heal the second they see that DoT show up on the status bar. Of course in my case, the first time I ran it (lvl 18-19) the fires spawned they snuck up behind me and immediately filled my screen murdering my framerate and then me. Downed it on the 3rd attempt, though I died when the guy was at 3% health or so.
I got nailed with it 3-4x in a row earlier (at 23), without my medkit I'd have died
but that's bad luck for ya.