bomber6689 said:
2) Go to the tall black building to the left of Green (from the starting perspective of her when the mission starts). You will spend 99% of your time there. When you get to the roof of the building (not the very top, the building is too tall, but rather the first roof), you should be just above her head. From there you avoid everything with ease. Her green missiles mostly hit the building, her rocks also hit the building, and the fire blast she does can hurt you, but if you jump a little you should avoid it.
I used the building to the front left with all the billboards on. Hunters and Evolved Infected will follow you up it, and you can nom them for health. The billboards completely protect you from Greene.
Also, you can jump down, hit her parts a few times with charged whipfist Y attacks for respectable damage, and run back up, good if you've not got Air Groundspike Graveyard.
5) Repeat until she faints. Then get down there and hack at her with the arm blade. When she goes away, get the necessary health orbs and get back on the building . Keep doing that and you should have her beat in no time.
When she goes down, hit her with Critical Pain. Takes about 1/4 of her health off and comes out fast so you don't get mobbed whilst you're trying to do it.