In his hand, this card gave Zo-Mar mastery over any and all people he showed it to! Even the strongest willed of us would be powerless to resist. Thankfully, Dru-Zod was able to knock it from his grasp before Zo-Mar could take over Fort Rozz.
For his crime, Zo-Mar was sentenced to lifetime incarceration in a satellite prison.
Zo-Mar survived the destruction of Krypton in his satellite prison, and eventually in August 1985 he finds his way to Earth. There, he uses the card to gain control over the Challengers of the Unknown and Superman. Zo-Mar who has no powers on Earth demands that Superman explain to him the secret of his powers. Under Zo-Marâ€™s influence Superman cannot help but tell Zo-Mar the truth that all Kryptonians have super-powers under Earth's yellow sun and lesser gravity and he does not know why Zo-Mar does not have them; however, Zo-Mar does not believe him and is convinced that he has found a way to resist his order.
In an effort to break Supermanâ€™s will, Zo-Mar orders him to destroy the town they are in. Powerless to resist, Superman goes on a rampage destroying every building in the town. Even though he cannot refuse Zo-Marâ€™s commands, Superman is able to use super-ventriloquism and his mimicry of Zo-Marâ€™s voice to give commands to the Challengers of the Unknown and order them to take the card away from Zo-Mar. Once they succeed Zo-Mar loses his control over Superman, but Zo-Mar suddenly gains super-powers including one power Superman does not have—the ability to generate some form of energy from his hands. Superman does not understand why Zo-Mar has this power, but he deduces the reason that Zo-Mar had no powers and has suddenly gained them: the card with the special symbol on it is made from a mutated form of kryptonite which robs any Kryptonian very near to it of his powers but which is not otherwise harmful and has no permanent effect. Superman uses his super-breath to draw the card away from the Challengers and toward Zo-Mar. When Zo-Mar grabs it he loses his powers. Superman, using split-second timing, punches Zo-Mar just as he grabs the card and knocks him unconscious before he can once again gain control over him.
Superman places Zo-Mar into the Phantom Zone to serve the rest of his life-long sentence. There Zo-Mar is surprised to find General Zod, the Kryptonian who had brought about his defeat on Krypton. There appears to be no animosity between the two men who each had failed to conquer Krypton however, as Zo-Mar says to Zod and Jax-Ur, "While the son of Jor-El roams free on a planet ripe for the conquering. We must plan together" (DCCP No. 84: "Give Me Power...Give Me Your World!").