He-Man and the Masters of the Universe Season 1 Episode 42 Eternal Darkness

Darkdream, an evil being who can control people's dreams, has been freed from the seal in which he was imprisoned, and is now using his powers to once again give the people of Eternia terrible nightmares. With his allies Evil-Lyn and evil magician Trebor, Darkdream plans to bring eternal darkness to Eternia so he can roam it freely and bring it his reign of terror once again...