She was from a pocket dimension where a bad guy named Onslaught pretty much took over everything and destroyed the entire universe. She originally sacrificed herself into the Negative Zone with the baddie, hoping to keep him there. (He was trying to take over our universe.) But she ended up in our universe, and it turned out that Onslaught had planned that all along. She had enough energy stored inside her to bring him into this dimension and he was using her as tether. She sacrificed herself, begging one of our friends who could control gravity, to kill her so that he couldn't make it into our universe the way he did hers. Nomad was her codename, but I just knew her as Rikki Barnes. I miss her.