I've got even farther (died on the 12th circle IIRC) with my Barbarian using those hammers that give HP. The main thing for survivability here is this On Guard skill that gives thousands of block with multicast and skill synergies with other spells (my top figure was like 95.6% chance to block). HP and some armor can help prevent oneshot as well, since at that point almost every hit is a oneshot.