Kingdom Hearts: Birth by Sleep/Aqua/Mysterious Tower

Open a chest to the left of the tower for a Shimmering Crystal and to the right of the tower for a Megalixir. Back at the other end of the path by a cliff is Magnega. Enter the tower and open the chest beneath stairs for a Mega Magic Recipe. There is also a Donald Sticker here that can be obtained with the newly-acquired Doubleflight. Climb the stairs for a scene in which Aqua receives some bad news and is directed to the Keyblade Graveyard. Afterward, she forges D-Links with Donald and Goofy and obtains Xehanort's Report 4. Once all other business is done, continue to the Keyblade Graveyard for a final showdown.