MR would work a lot better if 2/3rds of the enemies weren't Cursed. Unlike most other statuses (aside from Weaken and Corrosive) there's no immunity from items, and unlike every other status, no cure potion. Maybe Crusader? Heh. They're immune. I tried a couple of Berserker runs, thinking the MR would be clever. It was mostly irrelevant.
I blew 4K gold on runs between Assassin, Rogue, Berserker, Monk and Paladin - about 50 runs. No successes, although Assassin and Rogue both came within a few hits a few times, via Tikki Tooki (double Edge early via desecrations, the Dodging, and 2-3 Reflexes, depending on whether or not Pactmaker is also being fueled.) Prepped Magnet, Extra Altar, Midas Gloves, Apothecary, and Whupaz/Burn Salve/Reflex/Quicksilver/Mana pots.
Best I ended up doing was Elf Assassin with Whurrgarbl and Platemail both purchased right before the bosses. Assassins seems to be a good pick because they can actually deal with the illusions without getting screwed.