Watcher of the Roost

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.

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.

At any time, you can look at a face-down spell or permanent you control. You can't look at face-down spells or permanents you don't control unless an effect instructs you to do so.