Done!

15 min, zero deaths, 8 kills (not from me, as you can see 5 unknown and 3 Misadventure)
Granted its a lvl 19 and I'm 20...so might have to have lower testers, but its possible still. He was acting just like on normal, swinging aimlessly but if you keep moving around the top square you should be good. The only difference I did notice was there was at least 2 other trash mobs in the big room, might be where the "Misadventure" kills came from because they died when the puzzle was done.
Monastery Pic 1
Monastery Pic 2
On a side note, I dont think Sins of Attrition is in the right area...maybe needs to be Thuggery. I just tried it on Hard, there are too many unavoidable fights IMHO to be counted as Skulduggery. You have to fight the Cinderspawn and the Djinn to continue on, then you have to fight in the big room with the table. Then if you get past that (Cheat Death got me past it lol, barrier dropped when I died), you have to work through the hall spawns. The Orthons form a wall that you cant get past, I tried summoning an Earth Ele, but they agro'd on me after he died.
Just a thought, if anyone can do it w/o having to fight all that stuff, I'd be interested to know
OTW out to Sins, I came across
this named and went to /sleep right next to his worshipers (from the above post about /sleep lol) Just thought it'd be funny. Then I got up, blinded and vorpal struck him...like a black widow spider lol. It's pretty dark, kinda hard to see though.