He-Man and the Masters of the Universe (1983)

S1E42 Eternal Darkness

Darkdream, a malevolent entity with the ability to manipulate dreams, has escaped from his long-held prison and is unleashing horrific nightmares upon the inhabitants of Eternia. Teaming up with his sinister accomplices, Evil-Lyn and the dark sorcerer Trebor, Darkdream aims to plunge Eternia into perpetual darkness, allowing him to reign unchecked and spread his tyranny once more.