Editing Flood outbreak

{{Status|Canon}}
A '''Flood outbreak''' is a sudden increase in the spread of the [[Flood]] superorganism in a given span of time. Depending on context, outbreaks of the Flood may be localised to a small region, or may encompass large swaths of space.

==Stages==
Flood outbreaks typically go through a number of stages, progressing from the Flood behaving as mindless zombie-like creatures to incredibly intelligent organisms with the ability to operate starships and other advanced technology.
===Feral stage===
The feral stage is the first phase of a [[Flood]] outbreak. In this state, the Flood operates in a very aggressive manner, and their expansion depends on finding sentient life forms and expanding their overall biomass. Victims become hosts to the [[Pod infector|infection forms]], and are mutated into [[Flood combat form|combat forms]]. During this period of time, the Flood attacks with little to no strategy, seeming to focus primarily on consumption of intelligent beings and biomass and thus expanding and strengthening their own forces.{{Ref/Generic|Id=Bestarium|[[Bestiarum]]}}

The Feral Stage is typically initiated either by an outbreak of extant infection forms, or the infection of various sentient and non-sentient species by [[Flood spore]]s and other microbiological vectors. This infection soon becomes parasitic and causes the growth of Flood biomass in the hosts as well as the generation of new infection forms to further the infestation. At some point during the Feral Stage, the Flood begin to collectively shift their objective. When this happens, Combat Forms will work together to accumulate the biomass of both infected victims and uninfected sentient beings, allowing a series of widespread chemical reactions to occur across the reserves of [[calcium]] and flesh they have collected, eventually creating what is known as a [[Proto-Gravemind]]. Once a Proto-Gravemind has absorbed enough biomass and becomes a full grown [[Gravemind]], the infection can then proceed into the Coordinated Stage.{{Ref/Reuse|Bestarium}}{{Ref/Site|Id=wp flood|URL=https://www.halowaypoint.com/en-us/universe/species/flood|Site=Halo Waypoint|Page=Flood|D=17|M=7|Y=2021}}

===Coordinated stage===
The coordinated stage is the second stage of a [[Flood]] infestation, over the course of which a local ecosystem is typically fully absorbed - turning them into [[Blightlands]].{{Ref/Book|Enc22|Page=413}} During this stage, Flood population rapidly increases. The [[Flood Super Cell]] generates a [[Flood hive|hive]] and propagates [[Flood spore|spores]] into the local atmosphere in massive numbers. Once sufficient biomass has been gathered, the Flood gains the ability to spontaneously generate Flood Super Cells, removing its dependency on hosts and giving rise to [[Flood pure form|pure forms]].{{Ref/Reuse|wp flood}} On the verge of initiating the Coordinated Stage, the [[proto-Gravemind]] continues to be built until it reaches the status of a complete Compound Mind - a [[Gravemind]]. It is at this point that the Flood becomes significantly more organized (communicating via thoughts and attacking strategically) and subsequently more lethal than in the preceding Feral Stage.{{Ref/Reuse|Bestarium}} Upon the formation of a full Gravemind, all locally available [[Sentience|sentient]] beings have typically been absorbed by the Flood.{{Ref/Reuse|wp flood}}

Once it has gained sufficient technology, the Flood will proceed into the Interstellar Stage.

===Interstellar stage===
The interstellar stage is the third stage of a [[Flood]] infestation. The Flood progresses into this stage when it has the technological ability to leave a given stellar system.<ref name="bestiarum">''[[Bestiarum]]''</ref>

Although the initiation of the Interstellar Stage has less to do with the Flood's biological development and more with their access to viable space travel,{{Ref/Reuse|bestiarum}} in the latter phases of this stage the full extent of the Flood's power becomes truly evident, transcending beyond its purely biological aspects. In line with the parasite's strategy of utterly saturating all available channels of information,<ref>'''Halo 3''', ''[[Terminal (Halo 3)|Terminals]]''</ref> non-biological intelligences and data networks are targeted with advanced forms of the [[logic plague]], the Flood's information equivalent.<ref>'''Halo: Silentium''', ''pages 214-215''</ref> With the assimilation of entire planets and the development of planet-engulfing [[Gravemind]] forms,<ref name="sil186">'''Halo: Silentium''', ''pages 186-187''</ref> the Flood's collective consciousness' sheer intelligence and processing power enables them to manipulate [[neural physics]]. In the final years of the [[Forerunner-Flood war]], the Flood was able to control [[Precursor]] artifacts through this effect, which made them nearly unstoppable against the Forerunners.{{Ref/Reuse|sil186}}<ref>'''Halo: Silentium''', ''pages 188-189''</ref><ref>'''Halo: Silentium''', ''page 236''</ref> However, all Precursor artifacts in the galaxy were supposedly destroyed when the [[Halo Array]] was fired at the conclusion of the war, denying the Flood access to Precursor technology in later times.<ref>'''Halo: Silentium''', ''page 326''</ref>

This is the stage the Flood was in during the final years of the Forerunner-Flood war and the events of the [[Battle of Installation 00]]. During the Interstellar Stage, separate Flood infestations across the galaxy will eventually coalesce into one singular collective which will swarm across the entire galaxy in a spiral pattern, moving toward the galactic center in order to ensure no worlds remain uninfected. Once there is no more uninfected biomass left in the galaxy, the Flood is theorized to enter the Transgalactic Stage.{{Ref/Reuse|wp flood}}

===Transgalactic stage===
The transgalactic stage is the fourth and final known stage of a [[Flood]] outbreak.{{Ref/Reuse|wp flood}} This stage is reached once the Flood has consumed all sentient life in an entire [[galaxy]] and gained complete understanding of any technological and scientific knowledge that was present. By this time, it has reached a complete critical mass, which means it must depart to other galaxies for further reproduction, infestations, and new technologies.{{Ref/Reuse|bestiarum}}

During the [[human-Forerunner wars]], the Flood was driven outside of the galaxy. Doing this may have caused them to achieve the Transgalactic Stage as they were able to return to the Milky Way 10,000 years later when they made first contact with the [[Forerunner]]s on [[Seaward]], sparking the [[Forerunner-Flood war]]. This is likely, as prior to the [[Halo Array]]'s firing, [[Forthencho]]'s [[essence]] was sent down to Earth by the [[Gravemind]] to tell the [[Librarian]] what he was told by it. Among this information was that the primary Gravemind had consumed other galaxies, including at least 10,000 planets, reinforcing the possibility that the Flood has at one point in history reached this stage.<ref>'''Halo: Silentium''', ''page 321'' (''"This we were told by the Gravemind, the greatest of them, who has consumed ten thousand planets and brought entire galaxies to an end."'')</ref>

==Known outbreaks==
Several outbreaks of the Flood have occurred throughout history - some of the most notable are listed here. For more outbreaks, see [[:Category:Flood outbreaks|here]].
*The [[Flood#fFirst outbreak|first Flood outbreak]] occurred in [[107,445 BCE]], after the [[Ancestors]] came into contact with Precursor dust.
*The [[Forerunner-Flood war]] represented the most extreme spread of the Flood to date, resulting in the [[Great Purification]] to prevent the Flood reaching transgalactic stage.
*At some point, a large Flood outbreak occurred on [[Installation 05]]. The infestation was halted, though not eliminated, due to the capture of [[2401 Penitent Tangent]] by the Gravemind.
*The [[Covenant]] encountered the Flood several times throughout their history, and deployed [[Zealot]]s to deal with the problem using [[Temple Wraith]]s.
*A large Flood infestation had occurred on the [[Etran Harborage]] by [[2531]], though would ultimately be stopped during the [[Battle of the Etran Harborage]].
*A large [[Outbreak at the Containment Facility|outbreak]] occurred on [[Installation 04]] in September 2552, though was stopped before the Flood could reach interstellar stage.
*A large Flood outbreak occurred in the [[Threshold gas mine]] in October of 2552, though was stopped by a [[Raid on the Threshold gas mine|Covenant strike]] before the Flood could reach coordinated stage.
*In early November of 2552, the Flood outbreak on Installation 05 was let loose during the [[Battle of Installation 05]], resulting in the [[Fall of High Charity]].
*In late November of 2552, the infected cruiser ''[[Indulgence of Conviction]]'' crash-landed on [[Earth]], resulting in the Flood spreading across [[Voi]]. The city was ultimately [[glassing|glassed]] to stop the outbreak.
*The infected ''High Charity'' emerged over [[Installation 00]] in December of 2552 and crashed on the megastructure, beginning to spread Flood across the installation. The outbreak was stopped by the activation of [[Installation 08]], and High Charity placed under [[Quarantine zone (location)|quarantine]].
*In the post-war era, the UNSC continued to deal with various minor Flood outbreaks and deployed [[Flood containment Fireteam]]s to deal with them.
**In [[2556]], an [[Outbreak at Site 22]] resulted in the bombardment of [[Site 22|the site]] by {{UNSCShip|Saturn}} following the failure of ground teams to contain the threat.
*In [[2559]], the [[Banished]] let loose a large-scale [[Outbreak on Installation 00]] due to breaking the quarantine of High Charity.

==Sources==
{{Ref/Sources}}

[[Category:Flood]]
[[Category:Flood outbreaks| ]]