Quick Shot is one of Rocket Raccoon's abilities from the 'Galactic Guardian' directory, his Basic Attack, and one of the three abilities he begins with when added to your roster. With it, Rocky guns down his foes with a series of rapid shots from his dual blasters, dealing Energy Damage to anyone unfortunate enough to be in his way.
As a Basic Attack, Quick Shot requires no spirit to use, and is (by default) assigned to the Left Mouse-Button. Further ranks in Quick Shot increase the range of damage it can inflict.
An interesting property to note is that Rocky's shots alternate in a 'left-right-left' pattern, allowing a player to take down two enemies simultaneously, if they happen to be standing close together, and the player carefully alternates targets.