My most OP run was a very lucky ROW run as the huntress where I ended up with a +5 blooming glaive, +5 plate armor of camouflage, +8 ring of arcana and +4 ring of haste. I also had a +5 wand of regrowth for good measure. I've spent most of my time being invisible, dealing devastating surprise attack from outside of their range of attack and immediately disappearing before they could strike back, only to repeat again and again.
Grim stone gauntlets boosted for speed of attack combined with ring of arcana is also insanely OP. The addition of the ring of arcana really made crazy fun builds possible.
For this one I had another artifact that didn't work so well for my build and used a scroll of transmogrify on it, but I did get one from 9-10 with a blessed ankh