Okay, remember how the first seasons finale was a pretty straight forward episode yet they still had episodes that lead up to it (such as ticket master, suited for success, or the episode where they had shown Fluttershy storing the Gala dresses). I think they are taking a similar approach in season two, but a less obvious one at that. I predict that the Windigoes (from the hearths warming Eve's episode) will return for some reason in the finale. I also believe that letter was important and will some how be connected with the return of the Windigoes or some other matter in relation to this.