He-Man and the Masters of the Universe S01 E08 Siren's Song

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

After suffering yet another defeat at the hands of the Masters, the Evil Warrors retreat back to Snake Mountain where Evil-Lyn suggests turning the heroes against one another. As Ram Man peacefully fishes on a lake, the boat is hit by a large tidal wave. When Ram Man awakes, Sersi the Siren stands over him telling him that whenever he hears her song he will obey her every command. Little does Ram Man know that Sersi is actually Evil-Lyn in disquise!