Blastia are a variety of things; house-heating, water-pumps, lighting, barriers, weapons, and ability for those not of the Children of the Moon to use magic. [ Or those who don't know the Rizomata formula. ]

They are... a fraction of condensed aer, created by killing an Entelexeia and shattering the crystal that is left, and inscribing one of many formula upon it. Blastia does not... return, as much aer to the world as stable as it takes it in. Aer is... less stable, than mana, and from what I can tell, Eleth. Blastia ... tilts it a little to less so, which requires Entelexeia to come and consume it.

... It is also of the aer, but it seeks to consume it.