Page 1230 — Doubled Down

This and the Season Two finale-part-one's "You will be" are probably my two favorite moments in the entire show. Just something to be said about a rock-solid villain reveal.

In fact, any stories about villain reveals that worked well (or failed in spectacular fashion)?

Gallus (RD): OR… we could finish our short rest and work on freeing ourselves.
Smolder (RT): Now that we know they're friends of Cozy's…
Silverstream (PP): …they might be worth a shot, right?
DM: I promise this will be a short interlude.
Ocellus (TS): Maybe we could take control of the CMC while we're locked up?
Yona (FS): We could all vote on their actions together.
DM: If that works for you, it works for me.
Sandbar (AJ): Okay, we know roughly where Cozy's going – into that grate in the library. The Crusaders and I will go down there, find Cozy Glow, try to get her on our side against Neighsay, then come back to get you all. Sound like a plan?
DM: Sounds like a perfect plan with absolutely no failure points whatsoever.
Sandbar (AJ): Spoken like a person who knows something we don't.
DM: I'm the DM. I know everything.
Sandbar (AJ): <sigh> Let's just go. What do we find beneath the grate?
DM: Do the CMC follow?
Gallus (RD): The CMC go first.
Silverstream (PP): Aye!
DM: Beneath the School of Friendship is a deep, gently glowing catacombs, covered in crystal that has grown like the branches and roots of a tree. The halls of the cavern are very tall; you have to climb down one of the crystal branches just to reach the floor.
Smolder (RT): There's an adventuring dungeon beneath the school and it isn't common knowledge?
DM: The basement levels are off-limits, and, well, most ponies are rule-abiding sorts.
Ocellus (TS): Have any of our friendship studies mentioned something like this?
DM: When you hear Sandbar describe it later, you might be reminded of something called the "Tree of Harmony." Not far from the entrance, there are viewports into an even larger atrium on a lower level of the catacombs. A great rushing sound gets louder as you approach. Down in the atrium is a magic circle and a great swirling orb of magic above it, steadily growing larger and larger. And in the center of the vortex seems to be a pony… who you soon realize is Headmare Starlight.
Sandbar (AJ): Wait… Is all the world's magic disappearing… to HERE?!
DM: Sure feels like it.
Ocellus (TS): So is Starlight the cause of the crisis?
DM: The mare looks dazed and drained, incapable of setting herself free.
Smolder (RT): Not here willingly, then.
Gallus (RD): Wait… Cozy was super confident she could take over the school… and not just temporar– …No. No that's stupid. You wouldn't…!
DM: Wouldn't what, Gallus?
Sandbar (AJ): There's that smile.