For everyone who is asking about the tower key: Yes, the shape is a clue. Let's just say you need to fuse a lot of plasma swords, ice shurikens, and imperial leaves...
2/5. One point for an idea, one point for warning us. -1 point for being barebones, -1 point for not letting us drag the balls to merge them, and -1 point again for not showing the canvas when I first came here.