Within the top twenty-five issues which constitute The 100 Greatest Marvels of All Time*, we find coming in at No. 16 the 1993 X-Men #25--written by Fabian Nicieza, with art by Andy Kubert and Matt Ryan, its story bringing to a head the tense situation involving Magneto and his group of acolytes in his orbital base of Avalon.
*A twist on the 1969-81 Marvel's Greatest Comics concept, but instead took its title more seriously and solicited votes for the top 100 comics published by the company and, in a ten-issue series of trade paperbacks from 2001-02, counted down and reprinted the twenty-five issues which topped the list. (SPOILER ALERT: The No. 1 fan favorite turned out to be Amazing Fantasy #15, featuring the debut of Spider-Man.)
Underlying the conflict which follows between the X-Men and Magneto, as you may have already guessed, are the differences that Charles Xavier and his old friend/foe continue to have in their respective approaches to how best to safeguard the mutants of the world vis-à-vis their relations with homo sapiens--a very old argument between them that has once more led to Magneto taking a stand of force in his efforts to prevent mutants from being oppressed and/or killed by those humans who harbor hatred for them, rejecting Xavier's dream of integrating the two races in peace which Magneto views as futile. But in the story's appearance in the 100 Greatest series, Bob Greenberger (Director-Publishing Operations), in his foreword, reveals at least one of the two more prevalent scenes (while hinting at the second) which were likely responsible for this issue of X-Men coming to mind for the over 50,000 voters who filled out their ballots. (Which constitutes SPOILER ALERT #2--but perhaps a moot point, given that the issue is nearly thirty years old.)
But let's take things one step at a time, as we're first witness to what serves as the last straw for Magneto--what he considers an act of provocation when the powers of the world decide to implement the so-called Magneto Protocols, which leads the Master of Magnetism to respond with a reprisal that technologically cripples the entire planet. Consequently, the X-Men, who have the benefit of their equipment from the Shi'ar to help them recover, assess the stakes involved if they do not act decisively against him.
(NOTE: The splash page's dedication which mentions a thirty-year future for the X-Men, and the PPC's review today, thirty years after the issue's publication, is purely coincidental--honest!)
Fortunately, before throwing the world into darkness and chaos, Magneto managed to light a fire under Kubert and Ryan to provide an impressive wrap-around cover for this issue--which throws in (no pun intended) a Gambit hologram which regrettably can't be discerned in a two-dimensional representation. I'm not the greatest fan of such gimmicks, but it did look pretty cool when tilted at the correct angle.