He-Man/ThunderCats defeated villains and Cringer runs into He-Man's arms thrilled his best friend is alive. The three rush back to the ship desperate to get back to Eternia before it is too late. The four Ancient Spirits of Evil have arrived on the doorstep of Castle Grayskull while Skeletor and Mumm-Ra look on. Randor has assembled an army alongside the Thundercats and the combined heroes attack the giants. Man-At-Arms, Tygra, and Panthro assemble a cannon of combined Eternian and Thundarian tech to attack the Spirits while the others buy them time. Inside the Castle the Sorceress summons the Castle's defenses to
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.