Gurns sword attack is weak. What he kills you with is his magic. If you defend against his magic attack then you can take him out with ease. I did him in at lvl 13 with skull crusher and a couple of magic rings that everyone should have. I still had to use a couple of healing potions but the fight was a blast. And 1 of my friends even survived to ride the boat home with me. Potions of shock resistance are needed also.