When you place a Level 15 Epic Wubbox on Gold Island, it will assume a new powered down form. You will need to Box Epic Monsters on Gold Island in one of five Elemental Phases. This will remove them from their native Islands, as well as from Gold Island. As soon as the first Inventory is completed, you can Power up the Plant Phase and the Epic Wubbox will begin making music. Complete the other 4 Elemental Phases to unlock the Epic Wubbox's full song.