He-Man and the Masters of the Universe S01 E21 Snake Pit

"A sword will choose a master, a boy will become a man, and a hero will be born."

All of Eternia is put on high alert when Kobra Khan escapes from the Royal Palace prison compound. The Masters journey to the Mystic Mountains where they inform the mysterious Zokak of the situation. Skeletor is quick to employ the talents of Kobra Khan, unsuspecting of the Snake Man's intent on releasing his ancestors from a hidden void in Snake Mountain...