Onyx Sentinel

Summary
The Onyx Sentinel is a Forerunner-created electromechanical variable configuration and purpose machine. It has only been seen on the Forerunner artificial world known as Onyx, which was actually comprised of trillions of the machines. Whether the same model is on other worlds is currently unknown.

Appearance
The Onyx Sentinel shares a similar appearance to the Monitors - with a round sphere in the center, and with a central "eye" that glows golden. The eye is the cut-down Energy Projector. However, it also has three metal booms extending from equistidant points on the surface of the central sphere.

The Onyx Sentinel also has antigravity technology, not unlike the Covenant. Although the Onyx Sentinel can even reach escape velocity and fly into outer space, in ground operations, it normally engages its targets at a height of three meters.

Combat
It is extremely versatile, and is a powerful combatant on both the ground and in space. One of their primary advantages is a gold-colored Energy Shield that is completely resistant to all projectiles, even the rockets of the SPNKr Launcher and LOTUS Mine detonations. However,the shield is fouled by slow moving objects, such as a rock, which was used to destroy one Sentinel on Onyx.

It is also very adaptive, each Sentinel transmitting its combat footage to an unknown intelligence that continually upgrades Onyx Sentinel combat algorithms. As per a Spartan: "We are teaching it how to fight". The Onyx Sentinel's can also merge together for a variety of purposes, such as combining to increase firepower, architectural purposes, and forming clusters to protect Onyx.

It is far superior to the regular Sentinels that guard the Halo ring-installations, and even the Sentinel Majors and Enforcers, due to its shielding and extreme firepower: a cut-down Energy Projector firing golden, lethal spears of light. A single impact causes devastating damage; the destruction of a granite plateau, vaporization of a combat bunker, and the instantaneous destruction of any ground vehicle or infantryman, including even a SPARTAN-III. Enough Onyx Sentinels can even vaporize a large starship.