Rachel Summers claims the power of Phoenix, Jean Grey returns from a watery grave and the original X-Men reunite as X-Factor! It's an era of upheaval that puts Marvel's mutants on the path to some of their darkest days! Both Cyclops and Professor X leave the X-Men, but a new teammate waits in the wings: Magneto?! As Storm steps up and Wolverine faces the new Phoenix, the relentless Nimrod targets the team for annihilation! Meanwhile, the newly minted X-Factor grapples with Jean's miraculous resurrection and shares a fateful first encounter with Apocalypse! Plus: The X-Men and New Mutants enlist in the Asgardian Wars, Nightcrawler goes solo and Longshot debuts! Collecting UNCANNY X-MEN (1981) #194-209, X-MEN ANNUAL (1970) #9-10, NEW MUTANTS SPECIAL EDITION #1, NEW MUTANTS ANNUAL #2, NIGHTCRAWLER (1985) #1-4, LONGSHOT #1-6, AVENGERS (1963) #263, FANTASTIC FOUR (1961) #286, X-FACTOR (1986) #1-8 and ANNUAL #1, IRON MAN ANNUAL #8, AMAZING SPIDER-MAN (1963) #282, and material from MARVEL FANFARE (1982) #33, and CLASSIC X-MEN #8 and #43.