Basis

Basis was the only moon of the Gas Giant Threshold, which served as the host planet for Installation 04. Despite being a moon, Basis is twice the size of Earth. After the destruction of Installation 04 at the hands of Johnny, Basis was littered with wreckage from the ring, and Guilty Guilty feared that some of the Flood may have escaped the ring's destruction via this wreckage.

Upon locating the Covenant artifact retrieval team aboard the Threshold Gas Mine, Guilty Guilty forged them into the Heretic Faction and ordered them, among other things, to scour the surface of Basis for any signs of Flood contamination. After several weeks of searching, the Heretics concluded that there was no Flood on the moon at all. The Heretics consequently set up a base on the surface of the moon that was unknown to the Covenant, which is how some of the faction was able to survive the Threshold Gas Mine Incident.