At some point during the Feral Stage, the Flood begin to collectively shift their objective. This infection soon becomes parasitic and causes the growth of Flood biomass in the hosts as well the generation of new infection forms to further the infestation. 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 spores and other microbiological vectors. 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. Victims become hosts to the infection forms, and are mutated into combat forms. 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. The feral stage is the first phase of a Flood outbreak. 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.

The many system shock the flood halo