Spoiler warning for X-Men #12!
The X-Men have come under the guidance of Apocalypse - who used to be their greatest adversary - and his ultimate plan is taking shape. Since the beginning of the Dawn of X relaunch, the "blue warrior-god" has guided mutants as part of the Quiet Council, the secretive body that rules over the new mutant nation of Krakoa, and pushed them toward a quest to undo one of his most regretted mistakes. As the new issue X-Men #12 reveals, the next stage in his plot is to take mutantkind off of Earth completely and into a new realm.
The first indication of Apocalypse's agenda came in Powers of X issue 4, when the sentient island Krakoa revealed that it was once a much larger entity named Okkara. Five thousand years ago, a mysterious villain used the "Twilight Sword" to split the island in half and demonic invaders poured in. Apocalypse and his four children, the Horsemen, stood against them. In order to defeat the invasion, Apocalypse sealed away Krakoa's other half, Arakko, in another dimension, which meant leaving the Horsemen to fight the invaders eternally.
Apocalypse then formed the team Excalibur for missions into Otherworld, professing in issue 9 that his ultimate goal for them was to reach through the magical dimension Otherworld to recover his Horsemen. Over the course of Excalibur, Apocalypse's mutant minions have helped him raise his magical power, conquer a kingdom in Otherworld, and in Excalibur #12, form a gigantic portal to Otherworld from Krakoa from the bones of his kin.
X-Men #12 sheds more light on the purpose of the portal and how it relates to the imminent crossover event X of Swords. Arakko has been nested in the demon-haunted world of Amenth, where it has been sieged by Amenthi demons for millennia. Apocalypse's wife Genesis has continued her husband's lineage, guiding a nation of mutants that take after Apocalypse much more than they do Xavier and company. But some of Arakko's most powerful mutants, like The White Sword and Isca the Unbeaten, have switched sides and aided Amenth. The defeated mutants sent over a chunk of Arakko called the Arak Coral, and with it the Summoner, a mutant who can travel from Otherworld to Earth, to petition Apocalypse for help.
Apocalypse explains his plan to the Summoner straightforwardly: he's made a gate to the Otherworld, a "door home" as the Summoner calls it, with which to reunite Arakko and Krakoa. But he doesn't plan to pull them back to Earth; he tells the Summoner he's going to send "the whole of Krakoa across Otherworld" and join Arakko in enemy territory.
Will Apocalypse succeed? We know that X of Swords is about the First Horsemen clashing with the X-Men, so they will meet, one way or the other. But if that means all of Krakoa teleporting into a nightmare world ruled by demons, things will be even more dangerous for mutantkind than anyone expected.
X-Men #12 is written by Jonathan Hickman with art by Leinil Francis Yu, color by Sunny Gho, and lettering by Clayton Cowles, and is available now.