You don't want to fight anything that isn't magic, use your resists to get some good level catapulting going on early. Try and break into the mob "chain" early, around the 1s and 2s and then you can mostly just follow that to the boss, attacking mobs once to make them teleport if they are in your way. Use the potions, you'll probably only be able to use one or two against the boss depending on how many dark tiles you have. They give an experience boost and first strike, so use them as a finishing move.
Against the boss, you'll have to regen fight him. Whenever your health dips close to 0 chug a might potion for a little extra kick in your attack.
I think I used the Viper Ward too, maybe it is necessary.
Dunno how useful this would be but it's the only screenshot I could find of my run.
