Flamethrower

 is Lucca's 1st-level Tech and the first Elemental Tech learned in. Acid use this Tech as well. Lucca learns this very early in the game, and a common strategy is to make her learn it before going to Manolia Cathedral for the first time in the Middle Ages, since Naga are weak to it and you fight a bunch right at the start.

When enemies align themselves or collect into clusters, Flamethrower damages them all.

Description
Lucca raises her hand in the air and then points her gun at the enemy, with a line of fire coming out and hitting the target.