Ponyback Brigade

If a face-down permanent leaves the battlefield, you must reveal it. You must also reveal all face-down spells and permanents you control if you leave the game or if the game ends.

A permanent that turns face up or face down changes characteristics but is otherwise the same permanent. Spells and abilities that were targeting that permanent, as well as Auras and Equipment that were attached to the permanent, aren't affected.

Any time you have priority, you may turn the face-down creature face up by revealing what its morph cost is and paying that cost. This is a special action. It doesn't use the stack and can't be responded to. Only a face-down permanent can be turned face up this way; a face-down spell cannot.