The Shocker is a Beam Weapon. It fires a steady lightning beam at the target point (includes auto-targeting). The beam builds up an electrified status effect that can result in chain lightning as the charge is spread.
The Shocker is most effective against large groups of closely packed enemies, particularly standard OverCharge Drinkers, due to its chain lightning ability.
The weapon is less effective against Scabs, as they often tend to be more scattered, nullifying the chain lightning effect of the weapon.
Larger OD, such Herkers, are much more resilient towards the Shocker, which was meant to be used on multiple, weaker enemies.