Subterfuge Link

After killing an enemy, increases the Cast Speed of the next Mod or Skill Cast by 35%. Lasts 15 seconds or until consumed.

Find in The Flooded Room injectable on N'Erud.

Lore

The antennae perform several tasks simultaneously—projectile tracking, scanning enemy vitals, gravitonic manipulation of kinetic forces...

Essentially, it's guiding your bullets for you.

"Gravity is not a force but a particle field—like light or magnetism. As such, it can be measured and manipulated in a variety of useful ways. The discovery of the graviton is what makes modern space travel possible."