What is the name of the weapon created by Kuvira powered by spirit vines?

The weapon created by Kuvira and powered by spirit vines is called the Spirit Cannon. It is a gigantic cannon designed to fire destructive beams of spiritual energy, giving Kuvira a weapon capable of threatening entire cities.

The project begins when Kuvira orders Varrick to develop technology that can harness the energy of spirit vines. After Varrick defects, Baatar Jr. continues the work. Kuvira's forces also harvest spirit vines from the Foggy Swamp, treating the living spiritual growth as a military resource for the expanding Earth Empire.

The Spirit Cannon is mounted on The Colossus, Kuvira's enormous platinum mech suit, during her attack on Republic City. Its power is difficult to control, especially when it draws energy directly from nearby spirit vines. During the final confrontation, the cannon's unstable beam helps create a new spirit portal after Korra redirects it through energybending. “Plasma Cannon,” “Harmonic Blaster,” and “Spirit Ray” are not the weapon's canonical names.