Scope the area for the treasure chests to find a Chaos Crystal, Magnega and Wellspring Crystal . The Ice Cream Sticker is really easy to reach as well. Enter the tower once you are done and grab the Mega Magic Recipe from the chest. Climb the steps for a scene with Master Yen Sid. Head to the Badlands when its all done to trigger another scene.
Go to the Land of Departure for the final scene. After the events take place you are given the option of finishing up loose ends or finishing the game so choose the path that suits you best.