Five Color Horses is a joke.

But now we've got a commander.

What to do with Morophon, the Boundless horse tribal?

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Write a story about a changeling-led pony utopia?

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Well fuck, now I need to build the deck and get Morophon to be altered as Chrysalis-as-Cadance...

Here's what I've got. 2 Pegasi, 5 Unicorns, 13 Horses Earth Ponies (one of which also makes 5/5 white Horses Earth Pony creature tokens), and 6 Changelings (counting Morophon and Crib Swap). And 2 Human Soldiers that have or give Horsemanship (plus a sorcery that gives Horsemanship). Plus 2 cards that make 1/1 white Pegasus creature tokens with Flying (and Crib Swap makes a Changeling).

I've already got alters for Mirrorpool and Imprisoned in the Moon: