Defenders of the Earth (1986)

Season 1: Episode 26

After retrieving a vat of deadly mutant slime from Ming's laboratory, six of the Defenders (LJ and Kshin do not appear in this episode) are chased through a time warp and go back to the days of King Arthur. There, they meet and join forces with Prince Valiant who tells them that his wife, Alita, is being held prisoner by the evil Warlock who has stolen the fabled Eternity Stone. And, to further complicate matters, the mutant slime - which has already infected Mandrake - escaped from the Shuttle when the Defenders crashed into the sea and begins to spread.