Challenge of the Super Friends (1978)

On their day off the Legion terrorize an old woman wandering through their swamp. She summons an evil swamp demon to give them the power to create zombies if they deliver the SuperFriends to it. They do so by luring the heroes one by one to the swamp, starting with tricking in Batman and Robin with the Scarecrow disguised as Hawkman. When the real Hawkman shows up he and Green Lantern go to investigate and get captured as well. One by one the rest of the SuperFriends get captured. The Legion gets the zombie power and send their minions to rob a plutonium plant. But when they demand even more power and capture the swamp demon, they miscalculate and he turns the unstoppable zombies loose on the Legion and they are forced to aid the Super Friends to gain their help. The witch tells the Super Friends how to triumph - by tying them to dead trees with dead vines. The Friends capture the Legion but the witch helps out the other side to balance things out and the Legion escape once more.