From Destinypedia, the Destiny wiki
A rare ability, the Stormtrance is summoned by focusing Arc energies within and then unleashing them in a continuous stream of lightning, dealing damage to enemies targeted by it. As it deals damage the lightning spreads to other enemies, wiping out large numbers of enemies in a short amount of time. When upgraded, Stormtrance can emit a shockwave that repels and damages nearby enemies, chain lightning twice as far, or teleport short distances.
List of appearances