Legendary Dudes of Awesome
Revelation in Pain
Whenever a changeling suffers a lethal wound in combat, onlookers may roll Wits + Composure as a reflexive action. If the roll succeeds, the witness sees the changelings mien for a split second. Obviously, this hack doesn’t apply to changelings and other characters who could see the mien anyway. Rationale: The Mask requires some effort to keep up, especially in the face of pain and blood. An alternate version might be when the human takes lethal damage, he’s suddenly shocked into seeing the mien for that moment.
Note: I’m going with the original version, not the latter. After all, what’s the point in someone seeing through your mask unless a whole lot of people can do it at the same time?