Marvel's X-Men "House of X" event has successfully set up the X-Men for a whole new era, in a truly "new beginning" that has re-defined the characters and their world. With the final chapter of the story arriving in Powers of X #6, there were some major dangling threads that needed to be tied off - and one glaringly big one in particular: the mysterious 6th life of Moira X. Ever House of X revealed that Moira is actually a mutant with the ability of Groundhog Day-style reincarnation, fans have been tracking exactly where her various lifetimes have led - with the exception of that sixth lifetime, which wasn't referenced at all.
Now that Powers of X #6 has arrived, we know all too well why Jonathan Hickman kept this story thread secret up until the very end! WARNING: MAJOR SPOILERS FOLLOW!
As it turns out, Hickman didn't so much keep Moira's 6th Life a secret, as he did hide it in plain sight: The "X3: Year One Thousand" timeline that Powers of X has been unfolding since the beginning, is actually the story of Moira's 6th Life.
This major reveal is dropped in a scene where "The Librarian" character we've followed throughout the Year 1,000 timeline visits its "preserve" of the old world. There we find out that Wolverine and Moira are the only two mutants left in the future world, held prisoner by the Librarian as precious zoo exhibits. The Librarian and its race represent a new form of human evolution called "Post-humanity," which is basically a bio-engineered union of humans and machines that eventually becomes the dominant species of the future. As we see throughout Powers of X, the Post-Human race's agenda is to achieve technological feats great enough to attract the Phalanx to Earth. The goal is to convert the Post-Human world into part of the Phalanx collective, and in doing so, achieve a sort of "godhood" beyond the mortal form - one that would potentially give post-humans dominion over time and space - and even Moira's repeating lifetimes. Upon learning the Librarian's true goals, and realizing mutantkind's great mistake (overlooking the post-human threat), Wolverine and Moira stage a "jailbreak" by having Logan kill Moira, thereby kicking off her seventh lifetime.
The big game-changer of this pivotal scene in the Powers of X finale is that Moira's entire mission (from the violent attempts to assassinate the Sentinel creators to her alliance with Apocalypse for a future war with Nimrod) has been totally re-framed. Moira is (seemingly) the sole person in existence who knows where the evolutionary fight for dominance truly leads - and the only one who knows that the threat of Post-Humanity is out there. With Marvel's "Dawn of X" relaunch, this has now become the overarching story that's guiding the X-Men universe.
House of X and Powers of X are now done, with all six issues of each book currently on sale.