Shock Cannon
From Destiny 1 Wiki
Shock Cannon is a relic from Rise of Iron. It is the Arc version of Scorch Cannon from House of Wolves.
Shock Cannon has a limited amount of ammo. It fires devastating "sticky" shock rockets that deals arc damage upon impact. After landing a rocket on an enemy or a surface, players can hold their trigger to "power up" the rocket. After hearing 3 beep sounds, players can release the trigger to cause a explosion that deals significantly more damage (around 10k) in addition to increased blast radius. Players can use the rocket as a "mine" by landing it at a choke point and hold the trigger til the enemies get close to it.