WARNING: The following contains spoilers for X-Men #11 by Jonathan Hickman, Leinil Francis Yu, Sunny Gho, and VC's Clayton Cowles, on sale now.
In the most recent issue of X-Men, the mutants are thrust full force into Empyre when the Cotati aliens attack Krakoa. The alien attack presented a clear and immediate danger to the mutants living on the island, but fortunately one of Marvel's most powerful mutants in history was available to defend the island in X-Men #11.
Magik arrives in Magneto's chambers while he appears to be meditating to tell him of the attack. Magneto is not only ready to join the fight, but he tells Magik that he "may even dress for the occasion." At that moment, Magneto puts on a very familiar costume, his traditional red and purple outfit that hasn't been since since the beginning of House of X. This iconic costume is the Master of Magnetism's battle armor...and it's time to go to war.
Magneto wastes no time and charges straight into battle, relentlessly eliminating waves of his enemies with casual waves of his hands. After he witnesses a Cotati general mercilessly kills his fellow mutant and former henchman Toad, Magneto brings down several satellites onto the alien, quickly and decisively finishing the fight.
Magneto has spent a lot of time leading Krakoa as a member of the Quiet Council but has done little in the way of battles, preferring instead to act as an ambassador and diplomat, an elder statesman of mutantkind who almost always wore white. In this case, the Master of Magnetism reminds everyone around him just how powerful he is and why he is still one of the most feared mutants on the planet, and he wore the costume that carried him throughout years of battles with the X-Men to do it.
Once Magneto put on his armor and headed into battle, the tide turned in Krakoa. He strategically worked with Magma and Iceman to produce one of the deadliest combinations moves the X-Men have ever used, effectively repelling an extraterrestrial army in less than a day.
Once Magneto donned his red and purple battle armor, all bets were off. At least for a time, Magneto stepped back into the role he believes was always destined to fulfill, and became the savior of mutantkind once more.