X-Men by Jonathan Hickman Vol. 3

One era ends and a new one begins as Jonathan Hickman's acclaimed run enters the Reign of X!
In the Earth-shattering X OF SWORDS, the Captain Commander of Krakoa makes a fateful decision that will affect the island-nation's residents! And when the Shi'ar Empire asks the X-Men for help, Cyclops, Storm and Marvel Girl answer the call! Elsewhere, the door to the Vault swings open at last. But time moves differently in the Vault—and for the beings who emerge, it's been a very, very long time since they entered! And Krakoa's future is at stake when one of mutantkind's greatest threats re-emerges: Nimrod is online! Then, it's time for the Hellfire Gala—and a changing of the guard, as Krakoa's very first team of elected X-Men debuts!

Collecting:
X-Men (2019) #16-21