Yeah, whenever I think about the season finale, something like this comes in my mind. Why? Well, because... it was epic. But really, really epic. Thus I wonder: if the season finale was so epic, and there's still a season 4 (and 5? 6?), how epic could it be that one episode which will definitely conclude the series?
Maybe it's not what we're going to see on TV, but imagination is legit. When the end arrives... Rainbow Dash will be the only one remaining fighting for that waste land which once was the brightful Ponyville. After all, we're getting new villains every season so sooner or later we'll se somepony wanting to destroy the whole world (at least in my mind!).
Neh, whatever... here's my first 4000x3000 px, 11 hours working on it!
This makes me think of the PPG episode Speed Demon. That shit was terrifying when I first saw it. Him was an enemy so terrifyingly powerful the only way to beat him was to never let him get his foot in the door. Let your guard down for even an instant, and suddenly the whole world's gone to hell. If you had any further thoughts on how this could go/have gone, I'd love to see them drawn.