Hardcover collecting the X-Men crossover event The Twelve:
Uncanny X-Men (#371-380)Uncanny X-Men 1999, X-Men (#91-93, 94 (A Story), 95-99)X-Men '99X-Men Unlimited (#24 (A Story), 25-26)Gambit (#8-9)Astonishing X-Men (#1-3)Wolverine (#145-149)Cable (#71-78)X-Man (#59-60)X-51 (#8)X-Force (#101)X-Men 1999 Yearbook
— Description from Comic Vine community (comicvine.gamespot.com · https://comicvine.gamespot.com/x-men-vs-apocalypse-the-twelve-omnibus/4050-124888/).
