When the Krakoan era began, and Marvel's mutants found a way to conquer death, Magneto (AKA Max Eisenhardt) had already lived a long life of struggle, heartbreak, and sacrifice. So, it's not surprising that he gave up the Krakoan resurrection protocols to fit in with the culture of his new home on the planet formerly known as Mars, Arakko. He perished shortly after, and the citizens of Krakoa soon found themselves in a desperate war for existence against the anti-mutant organization known as Orchis. That war has gone badly, and now the mutants need their Master of Magnetism to get back into the fight.
Source：https://www.cbr.com/resurrection-of-magneto-al-ewing-interview/
