I really like the idea that the mask represents the character's molt and transformation. One thing I wasn't sure about, though: it feels like the character always uses the same mask. Could a bandit (or impostor) acquire new masks over the course of different adventures, or own several masks with different identities and abilities? I think that could be an interesting possibility, but I'm not sure if that's the intended design.
I also really enjoyed the random tables for the Mask Master. They make for a great starting point, and it's easy to imagine creating your own tables once you've played a few games. And I have to admit, I laughed out loud when I rolled "Dave" on the "From" table. 😄