A lot of walkthroughs will tell you that the key to winning the final battle with Brooke Augustine in the DUP headquarters tower is to just run around the room avoiding fire. Running around only works when acquiring new concrete powers from the core relays... you honestly don't have to move anywhere to win this battle. There is a column near the back of the room, near the small tv consoles, where you can stand and simply snipe her away - even on expert mode.