WARNING: The following article contains spoilers for Astonishing X-Men #5, by Charles Soule and Ramon Rosanas.

Professor X is back from the grave - but how?

Marvel Comics readers and X-Men fans everywhere were left shocked when, during the course of the 2012 event series Avengers vs. X-Men, a Phoenix-possessed Cyclops came to kill his father figure, Professor Charles Xavier.

Since then, the Professor had neither been seen or heard from, and for five years, all signs seemed to point to the fact that Charles Xavier was truly deceased. That is, until Astonishing X-Men #1 was released, by the creative team of Charles Soule and Jim Cheung. The issue ended with the last page reveal that, somehow, the one and only Professor X had returned, though the "how" of it all remained a mystery.

For the first time in five years, the X-Men's true leader had re-surfaced, a revelation that had fans asking how such a return could be possible, especially after being killed by something so powerful as the Phoenix Force in such a seemingly definitive manner. As the series progressed, we learned that Xavier was locked in a battle with the Shadow King, on the astral plane, with both super-powered telepaths using the X-Men like pieces on a board game. But still, the question of how Xavier survived remained. It would take four issues for Soule to finally give us the answers we sought, in Astonishing X-Men #5, drawn by Ramon Rosanas.

The truth of the matter is, Xavier actually did die at the hands of Cyclops -- or, at least, his physical form died. But as his spirit found itself in the void, drifting in the dark, it was snatched by his longtime enemy, Amahl Farouk, aka the Shadow King. And as soon as the Professor arrived in the Astral Plane, he found himself an unwilling participant in a duel of telepaths. Here, where the only limit is how deep you're willing to dive into your imagination, the two enemies waged countless wars and battles, scenarios dreamed up by both as they tried to best one another, a chess match between two of the most powerful telepaths in the Marvel Universe. The battle seemed to be never-ending, as the X-Men fought the villain on two fronts, both in the real world in London, as unsuspecting participants on the astral plane.

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For the better part of five years, while the X-Men have gone through trials and hardships like the arrival of their original counterparts from the past, the Axis event, a universal reboot in Secret Wars, the threat of extinction caused by the M-Pox and the Apocalypse Wars, the Professor has been fighting one fight, a single, never-ending battle. One that, according to him, feels like has lasted over a thousand years. And now, even with his X-Men involved, it might only get harder still -- though it's a decent bet that the odds of it finally coming to some sort of conclusion just got a whole lot better.