Defenders, The (1972 series) #16

The Defenders and Professor X witness as Alpha, the Ultimate Mutant, emerges from Magneto's machine. They try to fight him, but the creature shields itself with a force field. Magneto causes the entrance of the base to cave in, and then orders his creation to teleport him and the Brotherhood of Evil Mutants (Blob, Unus, Lorelei, Mastermind) away from there. Left behind, the heroes try to dig themselves out of the mountain, and while the Hulk stabilizes their makeshift tunnel the others get out to safety. The mountain collapses around the Hulk, but he punches his way out of tons of rock and returns to his team perfectly unharmed. Xavier does a telepathic scan and finds that Magneto and his forces have gone to the United Nations. Magneto demands that the United Nations acknowledge mutants as superior race and true rulers of the world. However the general assembly protests, so Magneto orders Alpha to lift the entire building and everyone inside high up in the sky. The Defenders follow and once again they all attack Alpha, but once again they are no match for him. Alpha easily defeats them, but having further evolved with each use of his power, he starts to rebel against his leader Magneto's orders. Xavier dares him to take a closer look at both groupings and re-evaluate their motives. Alpha does this and realises that the Brotherhood are evil and have bad intentions. Finding them nothing more than a group of arrogant, selfish children, Alpha transforms the Brotherhood members into children. After apologizing to Xavier and the Defenders, he returns the UN building to it's rightful place, and transforms into a being of pure energy and departs to the sky.