Elites
The Covenant Elite, standing over 8 feet tall, is a formidable warrior possessing enormous physical strength. While this allows them to rely on brute force if necessary, Elites generally prefer to take a tactical approach. Elites are usually equipped with plasma rifles and grenades, but have also been known to carry plasma pistols or Needlers as well; some Elites have been seen wielding strange swords apparently made of plasma. Their armor is similar in capability to the Master Chief's MJOLNIR system; it includes full body shielding which augments the Elite's natural resistance. There are several varieties of Elite, denoted by the color of their armor. A rookie Elite is blue; veteran is maroon; commanders are gold; Special Ops soldiers have white armor, and Special Ops commanders are black.

Grunts
The Grunt is the Covenant's standard frontline soldier, essentially cannon fodder. Grunts are cowardly and not very threatening on their own; however, in groups or when close to more powerful allies, they can be overwhelming. Grunts are known to carry a variety of weapons, including plasma pistols, Needlers and plasma grenades. Special Ops Grunts wear black armor and carry fuel rod guns or plasma rifles. Their armor contains a breathing apparatus to provide the methane they breathe, and makes them especially vulnerable to headshots. 

Jackals
Jackals are Covenant footsoldiers, often deployed as scouts or assassins. Their superior senses of hearing, sight and smell make them excellent guards. Nimble and quick on their feet, Jackals are weak nonetheless. To make up for their weakness, they carry a strong energy shield which they bear in front of them. Jackals exclusively use plasma pistols, and are capable of firing them at extreme rate, at the expense of accuracy. They are most easily defeated with plasma weaponry, which drains their shield, or grenades. A Jackal's rank is denoted by the color of its shield and whether it has a helmet. Gold shields outrank blue ones, and helmeted Jackals outrank non-helmeted ones.

Hunters
Hunters are Covenant assault troops with extraordinarily strong armor, in essence walking tanks. They stand 12 feet tall, but contract to approximately 8 feet in combat, so as to make a harder target. Their armor integrates a fuel rod cannon and a massive shield, which is constructed of a nearly impervious alien alloy and is sometimes used as a melee weapon. Hunters are not particularly bright and have a major vulnerability: their armor leaves several patches of flesh exposed. Shoot the orange area once with a pistol to eliminate a Hunter. Be aware, as Hunters always travel in pairs.

Flood Infection Form
The Flood infection form is the most basic form of Flood and the form from which all others are created, an insidious masterpiece of parasitic invasion. First, the infection form uses its motile tentacles to move toward the intended host, then makes a remarkable leap directly onto the host's chest cavity once in reach. It then sedates the host with chemicals excreted by its stingers, and once the host is unconscious it opens the chest cavity and proceeds to inhabit its nervous system, linking the host to the Flood hive mind. Infection forms are frail due to their balloon-like nature, which is easily popped, and they will detonate when coming in contact with an energy field. However, many infection forms detonating at once will cause your shields to fall precipitously, after which you will be rendered vulnerable.

Flood Combat Form: Elite
The Elite combat form is the result of the infection of a Covenant Elite by Flood spores. The Flood sculpts the host body to its needs, pushing the head back and over the shoulders and sprouting sensory tentacles. The Elite Combat form possesses remarkable strength, tenacity and speed. Even when unarmed, it is a threat; the modified arm-tentacles can be used as incredibly powerful whips. The use of plasma grenades is not advised, as the Elite form will often rush you in order to take you with it as it goes. A shotgun is the most effective weapon choice against an Elite Flood form.

Flood Combat Form: Human
The Human combat form is the result of the infection of a Human Marine by Flood spores. The Flood sculpts the host body to its needs, pushing the head back and to the side and sprouting sensory tentacles. The Human combat form possesses remarkable strength and speed, though it is more vulnerable than the Elite counterpart, and shows a preference for human weapons. Even when unarmed, it is a threat; the modified arm-tentacles can be used as incredibly powerful whips. The use of plasma grenades is not advised, as the combat form will often rush you in order to take you with it as it goes. A shotgun is the most effective weapon choice against a Human Flood form.

Flood Carrier Form
The Flood carrier form is a waddling, hulking mass of flesh. It is most likely formed from Grunts and Jackals, which the Flood apparently do not consider to be powerful enough for combat forms, or damaged combat forms. Although repulsive, the carrier does not appear to be threatening-- it carries no weapon and is fairly slow. However, those who underestimate the carrier will get an explosive surprise. Its unique method of attacking is to flop down on the ground next to a would-be victim and release the infection forms in an explosive rush that will kill an unprotected human. The best solution is to run past before it manages to detonate; the five or six infection forms it spews forth are less of a threat than the explosion.

Elites
Grunts
Jackals
Hunters
Infection Form
Flood Elite
Flood Human
Flood Carrier
Sentinel