Abaddon

The Organon was a rumored Precursor artifact of incredible power, believed by some Forerunners to be able to activate all Precursor artifacts. It was considered to be the most sought-after Precursor artifact by Forerunner archaeologists.

Several years prior to 97,445 BCE, Bornstellar Makes Eternal Lasting sought the artifact on both Edom and Erde-Tyrene using a pair of human guides to lead him to its presumed resting place in the Djamonkin Crater. Instead he found the Cryptum of the Didact, who stated that the Organon did not exist, at least not in the form imagined by the Forerunners.

Years later, the Flood revealed to the Librarian that the Organon was actually the Domain, a metaphysical information storage medium created by the Precursors and embedded within their ancient structures. Its takeover by the Flood in the last years of the Forerunner-Flood war allowed them to use Precursor artifacts as weapons, and so gain an edge over the Forerunners. When the Halo Array was fired, the Domain and all knowledge within would be lost forever, along with all Precursor artifacts.

List of appearances

 * Halo: Cryptum
 * Halo: Silentium
 * Halo 5: Guardians