He-Man/ThunderCats all sides, He-Man defeats them all with help from Randor. Back in Skeletor's lair at Snake Mountain he explains to Mumm-Ra that he could never wield the Power of Grayskull without it consuming him. But by mixing Mumm-Ra's ashes to a potion it will link Mumm-Ra's ever living power to him allowing him to use the Power Sword. Despite Mumm-Ra's protests Skeletor drinks the potion and summons the Power of Grayskull to him adding He-Man's strength to his own. He-Man suddenly is transformed back into Prince Adam in front of Randor who is horrified as his son collapses in his
He-Man be a descendant of King Grayskull (a powerful barbarian and a hero from Eternia's ancient past), who sacrificed his life in order to save Eternia from the Evil Horde and originally wielded the Sword of Power. He was the original owner of Castle Grayskull; his sword was concealed in the castle for centuries before being given to Prince Adam, who inherited his ancestor's own power channeled through the sword (thus giving added meaning to the phrase "By the power of Grayskull..."). This action-figure line combined elements from the He-Man universe into a cohesive storyline with biographies on the figures' packaging.