I thought this was a pretty decent season finale. I liked it more than last season's, which didn't hang together neatly at all.
Cozy Glow is a little Machiavelli. She's not powerful enough to compete with our heroes, so she does whatever she can to sabotage everyone above her. Draining Equestria's magic doesn't matter if she thinks she can con everyone into following her, and that's easier if she can lock up everyone more respected than her. Admittedly, this seems to have developed mostly in this episode, and it's hard to see how her original admission to the school fits into it. Maybe it doesn't, and she just learned all the wrong lessons while she was there.
I think Neighsay worked out all right here, inasmuch as he was never really a villain outside of his racism and pride, and even he was able to mend his ways after being kidnapped by the widdlest quootsiest dictator. I'm actually surprised Celestia and Luna marched on Ponyville in a time of crisis... unfortunate that the magic of trains was the first to disappear.
It's a little strange that all the animals the team has stopped get locked up in Tartarus.
Also, the chimera used to be able to talk.
One weird exchange:
That is the best explanation so far. Somepony should investigate.
We'll go.
Oh, no-no-no-no-no-no. Not without us, you wo— Wait. Did you say "we"?
I've finally learned that it's okay to count on your friends for help. Um, you do want to come, right?
...That's... what they do. They've all been doing that since season 1. Spike's the only one who doesn't usually get to come along.
Funny that Cozy Glow keeps wearing her taped-together Empress of Friendship crown at the end when she's leading the student mob at the end. The real key to being a heroic friendship team: Perceptiveness.
This season is really heavy on magical artifacts for some reason. Not really good or bad, just... odd. Having
one in a season was usually enough, but now everyone's got 'em. Apparently they should start stocking up, since they're better than normal magic.