Clarion

Clarions are a network of facilities constructed by the Forerunners on the Ark, consisting of a superluminal communications array capable of relaying instructions to the Halo Array. One such facility, known under the name of the Citadel, was the site of the final battle of the Human-Covenant War and the site at which the Ur-Didact fired the array at the end of the Forerunner-Flood war.

Overview
Clarion facilities host the interfaces for the supraluminal communications network that allow the Ark to send commands to the Halos, such as ordering them to fire.

Known clarions

 * The Citadel - the Clarion facility co-opted by the Prophet of Truth in December 2552, and the site of the final battle of the Human-Covenant War.
 * Epsilon Clarion - The sole operational Clarion facility operational as of 2559, located on Epsilon Spire.

List of appearances

 * Halo 3
 * Halo: Hunters in the Dark
 * Halo Mythos: A Guide to the Story of Halo
 * Halo: Divine Wind