Halo Alpha
Halo Alpha

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Knowing that monster firing a Battle Rifle at you used to be Kevin from 2nd Platoon is just creepy. That could be me.
— Specialist Archibald Berger [1]

A Flood Combat Form[2] is a sentient being that has been infected by the Flood parasite via an Infection Form or Flood Spores, mutating the victim into a basic combat unit for use by the Flood. They are extremely dangerous, but can be easily defeated when alone or feral. However, when under the control of a Gravemind they can be coordinated and deadly.


A Combat Form is not a natural organism, but rather a mutated host infected by parasitic Flood Super Cells implanted by an Infection Form. Successful creation of a Combat Form requires a host with sufficient biomass and calcium storage, and an Infection Form to infect the host. After mutation begins, the infection Form attaches with one of its tentacles to the host's spine, which it uses to establish a neural connection that allows it to command the host's nervous system, thus rendering command of the legs and arms useless. During the infection process, the host's internal organs are liquefied, and the nutrients from them are used to develop the tentacles and other appendages.

A host becomes a Combat Form after an Infection Form enters its body. Transformation involves brutal mutations that makes the host more suitable for combat. This process is presumably very painful and terrifying, and will eventually kill the host; though, in certain circumstances, the host will remain alive. Once fully transformed, the Infection Form has total control over the host's body and changes the physical appearance of the host to better suit its own needs (although an infected host will be roughly the same size as it was before). On rare occasions, this effect may be weakened by time in stasis for the Infection Form, allowing the host to regain some control, as in the case of Private First Class Wallace Jenkins.[3] Combat Forms retain the host's previous attributes, therefore they can wield weapons, and drive and board enemy vehicles. However, Infection Forms do not require their hosts to still be alive for infection. Even dead hosts are suitable for conversion into a Combat Form; infection forms can infect recently deceased hosts and reanimate them in much the same way as they would living hosts. Although the brain tissue remains dead, the victim's biomass and calcium reserves are sufficient to warrant infection.

In the initial stage of a Flood outbreak, the Feral Stage, Combat Forms communicate using pheromones and have one instinctual behavior; to secure new hosts to strengthen the local controlling intelligence. Once a sufficient store of biomass is available the Flood enters the Coordinated Stage, and begins forming Pure Form Flood, with the Combat Forms being used either as defensive units or calcium/biomass reserves.

Infected hosts are rapidly digested while being converted, which leaves the host severely ravaged and decayed, much like a corpse that has been exhumed a few weeks after its burial.[4] Flood infection is a rapid and efficient biological process, as it can take under a minute in certain cases. A group of Flood will occasionally go after Sentinels if they are perceived to be the greatest threat in the area, although they are unable to be infected by the Flood due to their robotic and inorganic nature.

Types of Combat Forms[]

A specific creature is needed for the infection and creation of a Combat Form. Of the various Covenant races, only a few species meet the necessary requirements. Species known to be immune to conversion include the Mgalekgolo/Lekgolo, whose complete lack of skeletal calcium (i.e. bones) and central nervous system, colonial physiology, and insufficient biomass per individual worm make infection and neural synchronization impossible for Infection Forms, the Yanme'e, whose exoskeleton lacks the required amount of calcium, which renders infection impossible, and the Huragok, which is an artificial, gas-based organism, and therefore believed to be immune. Even though the above species are immune to conversion into combat forms, they are still probably used for extra biomass.

All victims of the Flood's infection, regardless of their physiology, will undergo the reanimation process where the hosts will experience its skin decaying rapidly (if they were infected while alive), growing whip-like appendages which will serve as their primary melee weapon in close-combat situations and have their heads (which are useless to the Infection Form, as it is now in command of any and all neural activity) pushed aside. In Halo 3, the reanimation process can be witnessed; the host will twitch around in pain and eventually collapse on the ground. For a live transformation, the Infection Form will force the host's neck to be snapped, thus allowing the Infection Form to gain complete control over the host's body. Afterward, the whip appendages will force itself out of host's left arm, and the Infection Form will force itself out of the host's chest.

If available, the Combat Forms are able to wield the arsenals of the UNSC and those of the Covenant. In Halo 2, all Combat Forms are also capable of driving and boarding vehicles. In Halo 3, the Combat Forms lose the ability to drive vehicles, though they are still capable of boarding any slow moving vehicle and attacking the player with their whip appendages.

All forms of Flood Combat Forms have the capacity to easily escape from nearby grenades. Out of all of them, the Sangheili forms have the highest chance of evading grenades, often leaping away from them. Other Combat Forms, like the Jiralhanae, usually either ignore them or make a failed attempt to protect themselves from the blast. However, if stuck, Combat Forms may charge towards the player in an attempt to lower their shields or kill them.

Human Form[]

Human Flood Combat Form H3

A Human Combat Form

The Human Combat Form is significantly smaller than other forms due to their original smaller size. As with other Combat Forms, it is capable of sustaining massive physical damage before being unusable to the Flood Infection Form; in fact, as long as the chest cavity and legs remain intact, it will continue to fight. Although it cannot take as much damage as the Sangheili Combat Form can, the Human Form has some advantages.

It seems to be more alert and is quicker to melee an opponent. It also presents a smaller, harder target to hit, Infection Form, as it isn't protruding out of the body as much as those of Sangheili Forms. However, in Halo 3, the Human form becomes an easier target to hit; the Infection Form protrudes more out of the host's chest and becomes a visibly significant target, and it seems to be significantly slower.

They can take more melee hits than its Jiralhanae version, so it is advised to avoid melee combat with them apart from the Energy Sword or Gravity Hammer as these are the only two weapons that can destroy them instantly. If meleeing, try to aim for the Infection Form lodged in its chest for a faster kill, as hitting the head or arms barely deals any damage.

There are two animations for a live transformation in Halo 3, the former being that the Marine will hold their chest where the Infection Form entered and will fall on their knees and commit forced-suicide by snapping their neck. The host will then be on the floor, and the tendrils will tear out of their arms. The second animation is the Marine is forced a few steps back and then attempt to run forward. Afterwards, the host will fall on the floor and start thrashing until the tentacles snap out.

Sangheili Form[]


A Sangheili combat form

The Sangheili Combat Form is a formidable enemy as it is very agile and resilient. It is also capable of utilizing its host's armor abilities, such as active camouflage and energy shields, to assist them in combat. The Sangheili Combat Forms are slightly larger than the Human form and, as such, present a larger target.

In Halo: Combat Evolved and Halo 2, all of the Sangheili form encountered use one armor palette; the Sangheili minor's combat harness. In Halo 3 however, the Sangheili forms will retain its host's armor palette, though by default, the Sangheili forms spawn with a minor's combat harness. This is most likely due to higher ranks providing more resilience towards attacks; an infected Sangheili Major lasts longer than a Sangheili Minor.

They also tend to dodge grenades quite frequently in Halo 3.

Jiralhanae Form[]


Jiralhanae Combat Form

The Jiralhanae Combat Form is a formidable enemy and is more aggressive in combat than other Combat Forms and will charge towards an opponent recklessly; this behavior is most likely a result of the Jiralhanae's savage nature and preference for close combat.

The Jiralhanae Form is the most powerful in offensive capabilities because of their aggressive nature. However, they are the least durable out of all of the Combat Forms. It is bulkier and slower than other Combat Forms and as Jiralhanae cannot be infected until their Power Armor is destroyed, the Jiralhanae Form cannot make use of their host's armor abilities.

Despite their aggressiveness, Jiralhanae Forms are the easiest to deal with, as they provide an even larger target compared to the Sangheili Combat Form, and are far easier to destroy with melee attacks.

Spartan-IV Combat Form[]


Spartan Combat Form

The Spartan Forms are a Flood assimilation of a Spartan-IV supersoldier used in the virtual training simulations aboard the UNSC Infinity; the purpose likely being to train S-IV personnel to combat the Flood parasite in the event of a resurgence. The unusual aspect of these forms is their lack of an Infection Form controlling them, however this could be a result of spore infection, or even more simply the Infection Form is just left out of the simulation entirely. It is likely that the Spartan Form is a specialized unique form created within the simulation specifically to train Spartan-IV personnel against the absolute deadliest of Flood infantry. The body shape of these forms remain the same, except for the arm, chest and head having been deformed, giving the infected a menacing and more grotesque appearance. The Mjolnir armor has been completely purged, and as a result they have lost their shields, though their Flood physiology compensates for this. Although their simulation prevents them from utilizing firearms, it is likely within their physical abilities. However, they can utilize armor abilities making them extremely versatile opponents. It is uncertain whether actual Spartan-IVs control the forms within the simulation or if they are controlled by artificial intelligence. Unlike the tendrils of standard Combat Forms, the Spartan Form's unique claw is usually powerful enough to kill a fully-shielded Spartan-IV in a single strike. The simulations were probably designed so that the simulation Flood were overpowered compared to actual Flood. This concept is similar to how baseball batters put weights on their bats during training.

Spartan-II Variant Combat Form[]

The SPARTAN-II combat form is a Spartan-II exposed to the Flood infection that has never been formally encountered. A unique characteristic is the positioning of the infection form inside the cranial cavity of the host. This causes the host's head to grow substantially, splitting their helmet apart to accommodate for the Infection form's size. The rest of the body is almost completely intact.

This combat form is only encountered in the Infection gametype in Halo 2: Anniversary.

Unggoy and Kig-Yar Combat Forms[]

IMG 0691

A Kig-Yar Combat Form.


Bungie concept art of an infected Unggoy.

These forms do not appear in the first trilogy and are instead introduced in Halo Wars.[notes 1] Rarely seen in actual combat situations, infected Unggoy and Kig-yar are more commonly converted into Carrier Forms or processed for their biomass. These "building blocks" can be used to add to a Gravemind's superstructure or be molded into Flood Pure Forms.

Unggoy and Kig-yar Combat Forms have only been witnessed in the first recorded contact between the Covenant and the Flood. It is possible that these weaker forms were quickly ruled out by the Flood and determined to be a less efficient use of biomass after only just a few battles. They are weaker, slower, and easier to kill than their Sangheili Combat Form brethren.

Forerunner Combat Form[]

Forerunner combat form

A Forerunner Combat Form seen in a Terminal video

Though never encountered, countless Forerunner Combat Forms existed during the Forerunner-Flood war. One can be seen in a stasis tank aboard Installation 04 in the Halo: Anniversary Terminal videos, though it is seen from behind and is in shadow so it's full appearance is never seen. Another Forerunner Combat Form is seen as a simulation of the Didact infected by the Flood. Once again, the image is not clearly visible as the hologram is blurry, though one claw appendage is visible as well as other amorphous growths on the body.


Combat Forms can take extensive and sizable amounts of damage before being neutralized. Arms, legs and even heads can be dismembered before they are incapacitated. The weak areas of a Combat Form are its sensory appendages that normally develop on the upper chest. This is where the Infection Form has nestled, and the body is incapacitated if this area is destroyed by a projectile weapon. Combat Forms can be made harmless by destroying all usable body parts. While this creates the renowned Flood Friends glitch in both Combat Evolved and its remake, in Halo 2 and Halo 3, if both the normal and whip arms are destroyed, but the Combat Form is still intact, the Infection Form residing in it will abandon the useless host, disintegrating the body in search for a new host or attack the player itself.

In Halo: Combat Evolved, a Combat Form may feign death, before suddenly ambushing the player with deadly melee attacks. While it can cause a false sense of security, it loses the weapon it was holding (if it held one) and cannot pick it up when feigning death. This can be avoided by explosions, or by severely damaging it such as a point-blank range shotgun blast. In Halo 2 and Halo 3, Combat Forms are simply disabled when "killed", reviving only when an Infection Form arrives to reanimate it. This can be avoided by destroying the body completely, leaving behind few remains of the former host.

Human weapons are generally more effective against the Flood, as Covenant plasma weaponry is designed to debilitate targets by causing burning pain and structural damage to bodies, and the Flood cannot feel pain or be crippled.[5] However, In Halo 3, plasma-based weaponry and melee attacks, formerly weak against the Combat Forms in the previous two games, are now highly effective. Piercing weapons such as the Sniper Rifle and the Beam Rifle have little effect on Combat Forms. At a distance, explosive ordnance such as grenades and ranged weapons such as the Battle rifle or the Covenant Carbine can perform well against Combat Forms. Do note that Plasma and Spike grenades should be used with caution, as the Combat Form will sometimes ignore all other targets and charge players using such weapons at high speed. The Needler can be devastating, as the supercombine explosion will prevent it coming back to life in Halo: Combat Evolved, and will shatter it in Halo 2 and 3. In addition, the Needler's explosions will destroy an entire horde of charging Flood Combat Forms, similar to grenades and rocket launchers.

For ranged weapons, it is recommended for players to focus their fire at the sensory appendages that are visible on Combat Forms as successfully firing at one will immediately bring down a Combat Form. While fairly easy to achieve on Human, Jiralhanae and unshielded Sangheili forms, shielded Sangheili forms must have their shields stripped before they can be killed with a headshot. Dismemberment with ranged weapons is also recommended preventing Combat Forms from using their held weapons. As Combat Forms can carry a variety of weapons including powerful close-range weapons like the Shotgun and Mauler, both of which can easily kill a player if they are not being cautious, it is recommended to only use your own close-range weapons when there are no Combat Forms present with either of these two weapons.

Pain causes a weakening of the Flood Infection Form and allows the host, if still alive, to regain control albeit briefly. This is shown with PFC Wallace Jenkins.



  • In Halo: Combat Evolved, Combat Forms will not disintegrate from successive melee hits when they are dead like in Halo 2 and Halo 3.
  • Flood Combat Forms seem to take on physiological and biological changes throughout the Halo trilogy (due to graphical updates). these changes from game to game could be explained as part of the Gravemind's influence in attempting to create a better Flood soldier.
  • Human Combat Forms always have a screaming human face when infected. This is likely due to it being the last face the host made upon infection.
  • Some Sangheili Combat Forms retain their energy shields, while some do not.
  • Terminal 4 of Halo: Combat Evolved Anniversary shows what appears to be a Forerunner Combat Form in a specimen tank. Another of these, also in a tank, along with several Infection Forms can be seen being studied by the Librarian in Terminal 2 of Halo 4.
    • Both times, the specimen is viewed from behind and the specimen is partially concealed in shadow and cannot be seen fully.
  • Flood Combat Forms appear to have superhuman strength, as they are capable of wielding heavy weapons such as Rocket Launchers with one hand. Furthermore, their whip attack is capable of sending victims flying several feet.

Halo: Combat Evolved[]

  • In all of the Halo games, Flood Combat Forms always hold the Shotgun with one hand, and fire it without pumping another round into the chamber. They somehow manage to make the shotgun pump itself. A possible explanation for this is that the Flood has extended an appendage into/onto the Shotgun which allows it to use the Shotgun's pump as a body part, or the pump action just wasn't programmed into Halo: Combat Evolved.
  • Combat Forms in Halo: Combat Evolved don't tend to dodge grenades.
  • Combat Forms will run towards the player when armed. Both Human Combat forms and Sangheili Combat Forms will berserk when they have their arm that holds a gun shot off and will rush the player. Combat Forms that are unarmed will rush the player by default.
  • In the campaign level 343 Guilty Spark, if you stand on a light Bridge, the Flood Combat Forms will leap onto the bridge and get stuck. They will only be able to move by jumping at you.
  • If you shoot both arms off a Combat Form in Halo: Combat Evolved it will not be able to attack you and will simply follow you around. Players have dubbed this instance as creating a "Flood Buddy".
  • This is the only game in which an Infection Form cannot revive a dead Combat Form; instead they may just get back up.
  • In Halo: Combat Evolved, all human combat forms are bare foot. The reason for this remains unknown and is strange because human combat forms have shoes in Halo 2 and Halo 3. It might have undergone constant mutation but this is unlikely. This is very likely a design choice to make them look menancing.
  • During The Maw, a medium-sized group of Sangheili Combat Forms can be found at the back of the armory; the most interesting detail with this group is that their active camouflage is enabled, and are some of the few camouflaged Combat Forms in-game.

Halo 2[]

  • Halo 2 is the only game where the Flood are able to drive vehicles.[6]
  • When using the Grunt Birthday Party skull against the Flood in Halo 2, the effect of the skull will cause the plasma grenade explosion to occur when you shoot the Combat Form in the chest, where the Infection Form is.
  • Reflecting their enhanced intelligence, human combat forms still wear the armor they had on when they first transformed making it significantly harder to shoot the infection form in their chest. Sangheili forms also begin to make use of their shields, making them harder to incapacitate should their shields be active.
  • If you shoot both arms off a Combat Form, the Combat Form will walk slowly then explode, releasing an Infection Form. Only Sangheili forms will release an Infection Form, human forms will simply explode.
  • Flood Combat Forms have the ability to crawl on walls. This is easily observed in The Oracle and Sacred Icon.
944108-71537277 full super

All Halo 3 Combat forms on an infected High Charity

Halo 3[]

  • The Combat Form can pick up any weapon should it be near them when they "resurrect." They will also pick up two handed weapons such as the Plasma cannon and Flamethrower if close by. Like other weapons, they will wield it with only one hand. However, they appear to be unable to use such weapons, making them easier to deal with if their whip arm is removed.
  • The Combat Form's performance in CQC is inferior compared to Halo 2. Combat Forms regardless of the type are a great deal more brittle than in prior games, and can be destroyed with two or more melee strikes regardless of the weapon being used.
  • The Flood can no longer operate or hijack vehicles, and don't have the ability to sprint or berserk.
  • Probably to prevent the player from getting a big combat advantage from Jiralhanae combat forms during the brief time they are allies in The Covenant, or perhaps to prevent enemy Flood combat forms from overwhelming the player, weapons that would normally be picked up when a Jiralhanae combat form "resurrects" are deleted by the game's code, rendering them unusable.
  • Human and Jiralhanae Combat Forms utilize one model - the Human Combat Form uses the male Marine model (regardless if female or an ODST), while the Jiralhanae Combat Form utilizes the Jiralhanae Minor model, regardless of the rank.
    • Sangheili Combat Forms are an unusual outlier however - although they spawn using the Sangheili Minor model, there are also models for both Sangheili Major and Ultras, despite the fact that they are only available when directly infected. In addition to this, if a Sangheili Combat Form utilizing a Major or Ultra's harness is destroyed, rather than keeping the same color palette, they revert into that of a Sangheili Minor.
  • Human Combat Forms are the only Combat Forms that don't leave behind their heads when their bodies are destroyed.
  • Combat forms are capable of speech in an echoing voice. They usually speak for the Gravemind or quote their host.
  • A glitch made it possible for the player to become infected on Floodgate, when they die.
  • If a Combat Form's two arms are destroyed, the host will disintegrate and an Infection Form is released.
  • As with Halo 2, Combat Forms in Halo 3 can be instantly incapacitated by shooting the Infection Form lodged in their bodies, although they are far more visible due to their red appendages from the Infection Form - in Halo 2, this was very hard to see.
  • The "Flood Buddy Glitch" can be used in Halo 3 if one were to encounter a Combat Form with no weapon. Shoot off the host's head and then the tentacle arm. It will follow you but deal no damage. This is pretty much useless since the Covenant and Flood are never found in the same level except in the Citadel when the Flood are your allies, and on Floodgate, when you meet up with a squad of Sangheili for a brief time.
  • When a dead being is infected, it will jerk around as if it were still alive (although, no sound) this could be the host's nervous system reaction to the Flood infection.

Halo Wars[]

  • Kig-Yar that get infected, whether upgraded or not, would be equipped with a Carbine that, strangely enough, shoot Beam rifle shots. This remains true to ODSTs that get infected and will turn into normal infected Marines equipped with Assault rifles.
  • Unggoy Squads that get infected would be split into two different forms. One would be either a Sangheili Combat Form or Jiralhanae Combat form (Depending on leader) and the rest of the squad will become Unggoy combat Forms.
  • Sangheili Combat Forms are the only host infected Combat forms in Halo Wars that do not equip a weapon.
  • The Flood units are significantly weaker than they are from the other Halo games but are efficient in taking out Infantry.

Halo 4[]

  • Though technically not in Halo 4, the Combat Form appears in the new Flood game type, as the infected SPARTAN-IVs.
  • The only weapons they have is the Flood Claw, located on their right arm.
  • They are able to use Armor Abilities such as Thruster Pack, Active Camo and Promethean Vision.



  1. While no canon source ever denied it was possible for Unggoy or Kig-Yar to be converted, it was thought that they were unsuitable for conversion due to their small size and an assumed lack of sufficient calcium stores. Instead of using Unggoy and Kig-Yar as Combat Forms, the Flood typically used them as a type of 'nucleus' that a Carrier Form would grow around. The two species had originally been intended by Bungie to become Combat Forms, but limitations in resources and staff at the time of the formative years of the franchise led to the introduction into the fiction of the Unggoy's and Kig-yar's unsuitable status as Combat Forms. They would also serve as building blocks for a Gravemind. It wasn't until the release of Halo Wars that they were formally implemented in-game.


  1. Halo: Spartan Assault, Random Pre-Game Quote.
  2. Halo: The Flood, page 225: "The first of these combat forms he'd seen had once been Elites."
  3. Halo: The Flood, page ??
  4. Halo: The Flood, page 220
  5. Halo: Evolutions - Essential Tales of the Halo Universe - The Mona Lisa
  6. Halo 2, Quarantine Zone