I have a question? I'm really interested in the hollow cave classes and was wondering if there's any extra context for them? Like did I miss a movie? This idea seems more than good enough to be a movie. 
The fairies in hollow cave, are they born the same way as pixie hollow fairys? Do they have their own ruler or still follow queen clarian? Were they originally pixie hollow fairies but left for hollow cave because of their unpopular talents, are they shunned or considered a necessary evil? Does hollow cave have it's own dust? You'd need blue dust to create regular dust and blue dust is produced by the moonstone thingy and the blue moon so how would hollow cave fairies get dust if there supposedly is only one moonstone? (Unless there's secretly another they've had all along gasp!"