S1·E9 She-Demon of Phantos

For many years, the Royal Palace of Eternia has had shipments of photanium (the strongest metal in the Universe) from the moon of Phantos to make weapons with, but Skeletor intends to from now on step in and have the photanium all for himself. Man-At-Arms is given worthless ore instead of the photanium, and when the moon's ruler, Queen Elmora, puts up a fight against the plans, Skeletor casts a spell on her that ages her and turns her evil. Realising the metal they've been given is useless, He-Man and co. head to Phantos to see what's going on, only to find themselves on the moon where Skeletor now drives slaves mining for the metal...