"Mutant" means "change," and there was plenty of that when the Uncanny X-Men counted down to the Marvel Mutant Massacre - beginning with the trial of Magneto! Rachel Summers became Phoenix, and the Brotherhood became Freedom Force! Lady Deathstrike became a cyborg, Moonstar a Valkyrie, Colossus a killer and Psylocke an X-Man! And Sabretooth first set his clawed foot into the X-Universe alongside his fellow Marauders! Guest-starring the original X-Factor, Power Pack and Thor! Gods, Morlocks, talking frogs and more! Collecting UNCANNY X-MEN #199-213, X-MEN ANNUAL #9, NEW MUTANTS #46, NEW MUTANTS SPECIAL EDITION #1, X-FACTOR #9-10, THOR #373-374 and POWER PACK #27.