History: (Justice League of America I #4) - Carthan was charged with battling the Slyssa, the ancient enemy of his people, the Dryannans. He traveled to a barren planet to investigate its usefulness as a supply base, and was caught in an electromagnetic disturbance that made him invulnerable. He defeated the Slyssa and became a renowned hero on Dryanna. Drynna’s tyrant ruler Xandor feared Carthan’s popularity, so he targeted him for death, but realized he couldn’t be killed. He exiled Carthan to Earth and placed three engines of destruction around the globe. Cartham couldn’tleave Earth unless they were activated, and Xandor was counting on his code of honor to prevent him from unleashing doomsday on Earth. After learning about Earth’s champions the Justice League of America he was confident they could stop the engines. Pretending to be a villain he activated the engines, kidnapped Green Arrow, and dared the JlofA to save Earth. The JlofA were victorious, and freed Green Arrow, but Carthan imprisoned the team in a hollow diamond so he could explain that he was not a villain. Batman, who wasn't trapped, knocked him into the control panel of his ship, and Carthan couldn't dissipate the diamond. He showed Green Arrow the stress point of the diamond, and the archer used his skills to shatter the prison with a diamond-tipped arrow. The League forgave Carthan, and offered to help him topple Xandor, but he told them it was his responsibility.