Aura Blast is a spell necklace which deals charged energy attack. It's the first spell necklace players receive when starting a new game. It has the unique ability to be fired in a "half-charged" state, which deals less damage and doesn't include the helix-like secondary projectiles, but also only costs half as much aura.
Lunais' mother Selen gives her an Aura Blast at the very beginning of her journey. It is required to be equipped to advance through the introduction.