text: You may not turn a face-down spell face up. You may not turn a face-down permanent face up unless it would have morph while face up or an effect specifically allows you to turn it face up. Illusionary Mask's ability has you turn a face-down creature face up if it would assign damage, deal damage, be dealt damage, or become tapped, but not for any other reason. For example, if you use Illusionary Mask's ability to cast a black creature face down, you can't turn it face up just because it's being targeted by Terror.