Temptation the Sightless

Face-down creatures you control have exploit
(When this creature enters the battlefield, you may sacrifice a creature.)
Whenever you sacrifice a face-down creature you
may shuffle it into your library.
Whenever a face-down creature you control
exploits a creature you may pay {2}, if you do turn
it face up. If {r} or {g} was spent this way you may
then turn it face down again.