o/ just now seeing this. I highly doubt I'm the first to do it, Mag is actually pretty ideal for that fight. I didn't use any specific build, in fact I had to go back and generalize a bit by taking off the helminth ability I had on her. Mag's 3 will always refresh your shield gate, and gating the biggest factor in play for surviving in that fight. Otherwise, I used my general build. It could definitely be optimized with a nourish/energy nexus setup if you wanted to. Stay off the ground, stay away from the fragmented one when possible, and keep up rolling guard as much as possible.