Shade
From Halopedia, the Halo wiki
The Shade is a Covenant stationary gun turret used against infantry, manned in third person like a vehicle. They consist of a stand and a floating mobile turret-like seating with control systems to its gun. In Halo 2, the Shade is replaced with a new Shielded Plasma Cannon, which has energy shields around it, similar to a Jackal's. The gun fires three fairly slow, high powered bolts of energy.
It is possible to snipe a Shade-user off its turret, but one must aim above the centre which the red reticule usually denotes, and at the user itself, since the Shade protects the user. It is impossible to melee attack a foe off of a Shade.
