This is a brilliant take on what I feel was a Missed Moment Of Awesome
for the show itself. The girl who was trained never to show emotion is held captive by the spirit whose entire purpose is to steal faces as soon as they show emotion. Mai resolves to get out of the situation intact, while Koh throws everything he has at her, growing fascinated with her resistance and eventually coming to consider her a Worthy Opponent
. Both are remarkably in-character, and the writing is very fitting — it's subdued, almost emotionless; this makes it all the more creepy.