Oh, that's actually pretty easy.
I just basically put the armor on merc, and leave town in act 2 (just going outside, not in the sewers). He goes and pandas about slapping things while I shoot green exploding stars at whatever he's fighting. Eventually the game freezes and I have to alt tab into the crash screen. The reason I think it has to do with the debuffs is because I get some debuffs for one game, and eventually it crashes, and when the game rerolls, it ends up running a different same monster set and possibly a different debuff set. (I don't know if these are specific to certain monsters on normal, or just chance roll when the game is created)
I can uh.. even one up that. Attached the save file if you want to have a go at it.
Also, I don't remember exactly what I was fighting during the time, but I'll definitely take some time and do some runs tomorrow. (since it's 6:50am x_x) Afterwards, I'll let you know exactly what monsters I fought when it happens if you haven't already done so (or didn't decide to). I can't be sure if I'll be able to let you know what debuffs they'll have, but I'll try and keep track of those too. (You know, assuming they're put into the game just like the game rolls the monster types you fight. Example, in the sewers, skeleton fire archers instead of zombies and dozens of melee skeletons)