Legion of Super Heroes: Heroes of tomorrow

Legion of Super Heroes: Heroes of Tomorrow  is a 2006 animated movie based on the Legion of Super-Heroes television series. It premiered on television and was later released on home video. The movie was released to DVD on October 18, 2006 and made its television debut on Cartoon Network's Toonami block on October 22, 2006. The film take places three months after the end of the first season and features The Justice League and the Legion of doom.

Plot
In the 31st century, Both the the Fatal Five - Tharok, Persuader, Mano,  Emerald Empress and Validus- and the Legion of Super-Villains- Lightning Lord, Hunter, Esper, Tyr, Wave, and Ron-Karr. - attack the headquarters of the Legion of Super-Heroes, with the aim of capturing their time travel device. the Legionnaires try to keep them back but fail. the villains activate the device and travel  back into the 21st century. the Legion follows them to the past, where they ends up in Metropolis.

meanwhile, the Fatal Five and  Legion of Super-Villains head to  Slaughter Swamp (just outside Gotham City). where they meet the legion of doom and joins force to take down the justice league and take over the world. Else where, The legion meets up with an older Superman and the Justice League. Brainiac 5 Tells the League about the Villains and there true Plan, to destroy Earth's sun, wipe out humanity, and thus prevent the formation of the Legion.

Both The Legion and The League track down the Villains and (after a long Battle) subdue them, but fail to prevent an apocalyptic cataclysm as the Emerald Eye of Ekron  plunging into the sun. As the star cracks apart, Star Boy and green Lantern uses their Powers to reverse the fractioning. In the final scene, the Leaguers Thank The legion for all their and commemorate Their heroism and with that The legion Returns to the Future.