I've had two good run recently end when random enemies spawned with the unique sword that gives the revenge skill and subsequently one shot me. I was fighting the Bane of Orcs dude in the fort near the spawn and took 150 damage from that ability alone. I had 120 or so health at the time with 20 endurance and the best armor I could find. Any chance that enemies with the sword could not have access to this? No other unique has messed me up this much.