Holo-drone

Holo-Drones are small, mobile, spherical drones capable of remote use, using anti-gravity generators for propulsion, used for the creation of high-quality holographic realtime images. They are used for several functions, allowing face-to-face communication over relative short distance, providing holographic duplicate decoys of important personnel, and engaging enemy forces without risking allied personnel.

Sesa 'Refumee, the Sangheili leader of the Heretics based on Basis and a gas mine on Threshold, used one of these to taunt a Covenant Special Operations assassination team, and later used another two to assist him in battle as he tried to kill the one sent to kill him, the Arbiter.

They are relatively weak in battle, and a direct shot will result in static washing over their form, betraying their holographic nature. Though they possess rudimentary shields, and are somehow capable of using actual weapons, they don't seem to be dedicated combat equipment. Physically, they resemble unactivated plasma grenades able to slowly fly through the air, though slightly larger.