The Legend of Zelda: Link's Awakening
After finding all eight instruments, Link goes to the top of the island: mount Tamaranch. There he plays the 'Ballad of the Windfish' with the instruments. This breaks the egg; Link then goes into the egg. Here, he fights against the last monster. When he wins the battle, the owl reveals that he is a part of the Wind Fish's spirit, and the Wind Fish confirms that this world was only a dream.