Qarsi High Priest

If a double-faced card is manifested, it will be put onto the battlefield face down. While face down, it can't transform. If the front face of the card is a creature card, you can turn it face up by paying its mana cost. If you do, its front face will be up.

Any time you have priority, you may turn a manifested creature face up by revealing that it's a creature card (ignoring any copy effects or type-changing effects that might be applying to it) and paying its mana cost. This is a special action. It doesn't use the stack and can't be responded to.

Unlike a face-down creature that was cast using the morph ability, a manifested creature may still be turned face up after it loses its abilities if it's a creature card.