Warbird assassinated her sister, Lilandra Neramani to become Empress of the Shi'ar Empire. She then became the Horsemen of Apocalypse, War, and assisted in the invasion of Earth by the Empire. They were confronted by the X-Men and Excalibur. She was going to kill Iceman but was stopped by Storm, after a short battle, she sentenced the entire X-Men to death but was stopped by the arrival of Professor X who used the full extent of his powers to knock her back. The Horsemen were driven away by Jean Grey and Mastermind pretending the Dark Phoenix had returned.
Powers and Abilities
Seemingly Roderick Campbell (Earth-616)#Powers.