Once Mickey, Donald, Goofy, Sora, Riku, Kairi, Asha and Valentino reached Mickey's palace with a secret doorway, Mickey knew this day would came.
Mickey Mouse: Asha, there's something I've been meaning to tell you about King Magnifico.
Asha: What about him, Mickey?
Mickey Mouse: I've met him a long time ago when I first arrived at Rosas after mastering the resurrection spell to revive Willie the Opera Singing Whale.
During the flashback, Mickey and Yen Sid were present at the throne room.
Mickey Mouse: (offscreen) Back then, I was an apprentice to my mentor Yen Sid and was about to be granted with one wish.
King Magnifico: Imagine a place where wishes come true. Where your heart's desire can become a reality. What if I told you that Rosas is my kingdom I found within reach? All you have to do is give your wish to me.
Mickey Mouse: And you'll let me make my wish a reality?
King Magnifico: I give you my word.
Yen Sid: The choice is yours, Mickey.
Mickey Mouse: (nodded) I'm ready, King Magnifico.
King Magnifico: Good. Now, close your eyes and look deep inside your heart.
Just as Mickey did as he said, his wish appeared from his heart. Once he looked inside it, he could see being a greatest sorcerer just like in his own dreams.
King Magnifico: Now then, Mickey, you can now give me your wish for safe keeping. (as he noticed the look in his eyes) Mickey, give it to me! (reaches for it as Mickey pulls it back) Give me your wish, Mickey. (as Mickey looks strange when he speaks to him sternly) Mickey! Give me your wish.
Mickey Mouse: No.
King Magnifico: What?
Mickey Mouse: I said "No", it's my wish for me to keep that you cannot take what's rightfully mine. I'm sorry, King Magnifico, but I don't trust you. (as he placed his wish into his heart)
Yen Sid: A wise choice, My Apprentice.
King Magnifico: (angered at Mickey) You will regret defying me!
Oswald the Lucky Rabbit: No he won't.
Yen Sid: (stops Magnifico) Enough, Magnifico! My apprentice decides what's best for himself and he chose wisely to let his wish come true, but if you try to abuse your power as king and use your sorcery for evil, it is you who will regret this.
King Magnifico: (to Mickey sternly) This isn't over, Mickey, you have been warned.
And so, Mickey and Yen Sid left the place and returned to their kingdom.