I find stam dk much easier to clear than mag dk. I would respec for damage. Level dual wield and bow. I like corrosive ult for some of the trickier fights like the Wamasu and others.

I like VO (vicious offidian) for sustain and night mothers gaze for pen but any damage set is ok. I use chudan....which gives a bit more tankiness (24k resists in medium). Dragon scale wings are very useful on the ranged add stages, 3 5 7 and 9.

Mag lacks mobility which can be crucial in there. Learn where the sigils are and when to use them. Joy's guide is very helpful to get a plan for the stages.