So.... apparently Gameloft has now given all of the Mane Six their own Nightmare Forms:

(Source)

I like the comment on Pinkie playing dress-up.

All of them look absolutely awesome!

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While these are some really neat designs, it does bug me that the official name they resorted to was just "Nightmare" followed by the characters' names. It's incredibly lazily done and doesn't really convey anything about what would actually be good names to represent their antithesis. Luna was called Nightmare Moon for a reason, and the same goes for Celestia as Daybreaker. Rarity had little reason to be called "Nightmare Rarity" and so on.