Marvel's Greatest Comics #84

At the helm of the Atlantean army, Magneto finally conquers New York City. Holding Sue and Lady Dorma as hostages, Magneto tries to force Namor and the Fantastic Four into swearing an oath of allegiance to him. Instead, the heroes counter with a weapon built by Mr. Fantastic that is able to turn Magneto's own powers against him. Prince Namor and his army return home, and there is once again an uneasy truce between Atlantis and the surface world.