It's crossovers aplenty in this final volume of the original X-Factor's adventures! First, the island nation of Genosha targets all three X-teams - X-Factor, the New Mutants and the X-Men - for X-tinction! Then, the X-teams reunite and ally with the youthful New Warriors when the reality-warping Proteus returns! And when Apocalypse attacks X-Factor in a savage and very personal way, the cost of defeating him may be more than Cyclops can bear! Finally, the X-Men battle X-Factor when the telepathic Shadow King launches his hateful endgame - and in the aftermath, the two teams must question if they are stronger standing apart, or joining together again!