Conquerors of the Future

To everyone's surprise, including the Super Friends, the Legion of Doom becomes the Legion of Good! But it's a ruse while they conquer the Earth of 3984 with the help of a merciless race of magic beings known as the Barlocks. However, the Super Friends put together the Riddler's cryptic clues and Superman, Flash, and Green Lantern travel to the future to defeat them there and liberate the inhabitants. However the Riddler tricks them into going 10,000 yrs into the Future, where they encounter giant spider-like creatures. Superman finds a history book and discovers which year the Legion traveled to. He and the other two go to 3984 and for the first time the Legion is captured.