From Destinypedia, the Destiny wiki
A Chronology Rifle is a Vex weapon used exclusively by Dendron, Root Mind, during A Garden World Story Mission and Strike. It functions similarly to the Laser Rifles used by other Vex units and Trace Rifles wielded by Guardians, but is much more powerful. The giant beam of energy can easily kill a Guardian in mere seconds if they do not get out of its way. This weapon is made more dangerous when Dendron circles around the battlefield, as it can sneak up behind Guardians if they are not aware of the situation.
List of appearances