Sora's next destination is a strange world called the Symphony of Sorcery, where he sees Mickey wielding powerful magic. The Spellican appears and rams into him, knocking Sora out. When he comes to, he finds himself back at the Mysterious Tower, but still in his younger body. He finds Mickey asleep, but he is still casting magic. Mickey communicates with Sora telepathically and tells him that he's Yen Sid's apprentice. After seeing Sora's Keyblade, Mickey asks him whose apprentice he is, but Sora doesn't have an answer because he's been self-traned. He says that the Spellican is using dark magic, but Sora can't reach it without using an item called a "Sound Idea" to dispel the magic. Mickey summons a musical score that contains a path to the Sound Idea. While Sora goes to find it, we see a flashback in which a curious Mickey put on Yen Sid's sorcerer's hat and cast magic, which drew the Spellican to him.
After travelling a long way, Sora finally finds the Sound Idea. Before he can grab it, the Mysterious Figure approaches him. He reflects on the beauty of the world and tells Sora that he isn't part of the dream or the Mark of Mastery exam. He tells Sora that if he remains asleep, they will meet again soon. After he vanishes, Sora takes the Sound Idea back to Mickey. After using it, the dark magic still doesn't fully go away. Mickey tells him that they may need another Sound Idea, but thankfully Riku finds it for him. Sora uses both of them to access the Spellican's domain. After a fierce battle, he manages to destroy it. Returning to the Mysterious Tower, Mickey wakes up and thanks Sora. The final Sleeping Keyhole appears, and Sora unlocks it. The Mark of Mastery exam should be over now, so he leaves the world, but he will soon find out that the true test is only just about to begin.
Back in the real Mysterious Tower, Yen Sid is musing what Lea has been up to: Merlin and the Good Fairies sent him to train in a time vacuum in the hopes that he can learn to wield a Keyblade. They begin to wonder whether or not Xehanort could have followed Sora and Riku into the Sleeping Worlds. Since a version of oneself has to exist at the destination of time travel, that would mean that an incarnation of Xehanort would have to have been at Destiny Islands on the night of the storm for him to follow them. What's more, Xehanort would have to have given up his body for time travel to work. Mickey suddenly remembers that Ansem was without a body prior to possessing Riku, meaning Xehanort could potentially have followed him and Sora into the dreams. Mickey figures that Sora and Riku will return to the real world soon if everything goes according to Xehanort's plan, so he goes to wear he thinks Xehanort will show up. Donald and Goofy want to accompany their king, but Mickey tells them to stay behind. Yen Sid tells Mickey that he sensed Riku in the Realm Between, which narrows down his potential location. With that, Mickey goes to find Sora and Riku as their Mark of Mastery comes to an unexpected end...
