Icefeather Aven

Morph lets you cast a card face down by paying 3 generic mana , and lets you turn the face-down permanent face up any time you have priority by paying its morph cost.

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.

The face-down spell has no mana cost and has a mana value of 0. When you cast a face-down spell, put it on the stack face down so no other player knows what it is, and pay 3 generic mana . This is an alternative cost.