Transgalactic Stage

The Intergalactic Stage is the fourth and final known stage of a Flood outbreak. 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.

The only known period when this stage was achieved by the Flood was when it first entered the Milky Way Galaxy and made first contact with the Forerunners on G617 g1, sparking the Forerunner-Flood War.