Soul burn Dagger - always pick trait slots +, chance for soul burn, and general upgrades for the special
Amulet: always get special plus

Use the soul burn as often as possible, and punch enemies away after soul burning, use dodge very often and watch your enemies melt away into puddles.

I always use it on any ranged enemies first, or one on ranged and one on the captain. By the time you get to the captain you can just soul burn, swing at him and recharge your soul burn, and once he turns special, you just soul burn and run.

With this run you can easily complete nightmare, I did challenging without taking a single hit, it's the game on easy mage mode.