An old dungeon monster design that I fixed up and finished. Frostburn Moths are telekinetic monsters with wings that function as portals, the gems as power stores. Using it's psychic abilities, it summons forth amplified flames, icy blasts from it's cold, natural habitat outside or even other creatures in the dungeon to defend itself.
They are energy leeches, often acting as an anti magic barrier when more of them inhabit a zone. If they consume enough excess energy, it is combined together and formed into another crystal. This means another wing and another attack turn. Reports from half dead travellers have stated the most they have escaped from is a 6 winged Frostburn Moth. The gems themselves also seem to be their eggs, on death the gems hatch into larvae and fling themselves into the fading parent's wings, away from harm in order to grow and take their place.
"Tamed" Moths have been used as town gateways for convenient travel, though due to their mischievous natures and general dislike of being bossed about, destinations may vary. If you want to not end up walking off a cliff or worse, it is advised to buy a source of energy as a form of payment.