X-Men Milestones: Age of X

In 2020, Marvel collected Mike Carey's "Age of X" storyline—a self-contained alternate-reality epic where the X-Men's greatest threats have already won—into a single "Milestones" hardcover. Featuring art by Carlo Barberi, Gabriel Hernández Walta, and Mirco Pierfederici, this one-shot volume distills the tense, fortress-era saga of mutants under siege into a definitive, accessible package. It matters as a key example of the franchise's willingness to explore dark, what-if scenarios that redefine the core struggle of the X-Men.