Siena Blaze originally started out as a member of the thrill-seeking Upstarts, a group of mutants who hunted other mutants for sport. She was recruited by Trevor Fitzroy when she was being chased by police with her boyfriend. Fitzroy arrived and killed her boyfriend, although she said she didn't care that much. He then killed many police also to create a portal to teleport them away. As a member of the Upstarts, she participated in several confrontations with members of the X-Men, such as Nightcrawler and Marvel Girl, when she was hired by Mr. Sinister, and an incident in Antarctica where she battled Cyclops, Professor Xavier and Storm.
Later she was transported to the Ultraverse along with Juggernaut and Reaper, where she was a member of the heroic Exiles (not to be confused with the current team of reality hopping heroes). Surprisingly, Siena adapted to the role of hero quite well. She felt a strong attraction to team leader Warstrike. Eventually she, along with Juggernaut and Reaper, were returned to the Marvel Universe.
Neverland and Necrosha
Afterwards Siena vanished from sight for years, until she met her demise at the Weapon XNeverland concentration camp.
However, she has recently been seen resurrected by Selene, and fighting for her on Utopia.
Siena can disrupt a planet's electromagnetic energy spectrum, absorbing the energy into her body until she releases it, usually in the form of destructive blasts of energy. The released energy would tear a hole in the local electromagnetic field and repeated use of her power would theoretically destroy the planet. Even limited use of her abilities could potentially cause catastrophic ecological changes to the planet. She can also use magnetic energy to fly at 150 mph or to teleport herself along the planet's electromagnetic field, but every time she teleports she permanently damages the field at the point of departure, causing a powerful explosion.