Rainbow Dash as Mr. Freeze

Rainbow Dash from MLP: Friendship is Magic dressed as Mr. Freeze from Batman.

It isn't any particular Mr. Freeze costume, although it does take a few elements from the Animated series and Arkham City versions.

It makes sense to me. She's blue, likes being cool, and can control the weather.

I originally gave her a freeze gun [link] but that didn't seem right. Luckily the Nightmare Night episode aired with her playing with a storm cloud so now she has a storm cloud shooter. I was also thinking about making her bald... and that was all kinds of wrong.

Originally, I wanted this scene to mimic Mr. Freeze's first appearance in Batman:The Animated Series. Twilight, as Batman, would be frozen in a block of ice. Derpy would've been the hapless henchmen who gets his legs frozen. But when I came up with idea of casting Gilda as Nora, I couldn't fit all that into the picture. Something had to go.