Plot: Using the power of the Medallion of Serpos, King Hssss transforms Snake Mountain into the mighty snake god, Serpos! Serpos begins to cause great destruction on Eternia, beginning with a vicious attack on the Royal Palace, then turning his attention on Castle Grayskull itself. He-Man and Zodak must combine forces to save the Masters and stop King Hssss from ruling all of Eternia!