Supernal Spiral-class keyship

The Supernal Spiral-class keyship is the most common classification of Forerunner keyship. Vessels of this class were used during and after the Forerunner-Flood war to collect specimens from various planets, safely transport them to Installation 00, and then return to those same worlds to reseed them with life following the activation of the Halo Array. As is implied by its classification, these ships can act as keys to activate slipspace portals place in strategic locations throughout the Milky Way.

The most notable of the Supernal Spiral-class keyships is Anodyne Spirit, or Forerunner Dreadnought, as it was known by the Covenant. Originally assisting with the Conservation Measure, Anodyne Spirit crashed on the San'Shyuum homeworld of Janjur Qom where it became the focal point of their religion, ultimately kickstarting the formation of the Covenant and later becoming the centerpiece of their holy city of High Charity.

Hull and superstructure
Supernal Spiral-class keyships are geometric and angular, having a tetrahedral shape consisting of a forward triangular prow with three similarly-shaped struts jutting out from its Primal Crux. Their hulls are gray and silver in color. While most Forerunner vessels crafted by the Builders could reform themselves into different geometries, the form of the Supernal Spiral-class keyship was fixed, maximizing strength and unity of purpose at the cost of flexibility. When resting on its landing struts, the Supernal Spiral-class keyship has a height of 13,120 meters, a width of 12,441 meters, and a length of 10,774 meters. Its total mass is 19 billion metric tons.

Internal layout
As would be expected given their massive size, the interior of Supernal Spiral-class keyships consist of numerous rooms, many of which are docking bays and control rooms, including command chambers that are many stories high. A series of lifts allow access to many levels of the interior of the ship. The three landing struts store the ship's cylix specimen receptacles within large, cavernous rooms. A location of note within the vessel is the Adytum, where the slipspace flake used to open slipspace portals is stored.

Armament and defense
Despite their purpose of conservation, Supernal Spiral-class keyships are equipped with powerful weapon systems including a single light mass fusillade cannon and three anti-ship artillery systems. As the San'Shyuum Reformists could not access these systems on Anodyne Spirit, they modified the vessel with their own weapons, using the keyship's own energy systems to give the weapons extreme power. However, these weapons were removed when the keyship was later decommissioned.

While the Supernal Spiral-class keyship's primary defense is its speed and agility, they are fitted with an extensive suite of defensive countermeasures including a powerful prime dispersal field generator. They are even fitted with the ability to remotely detonate the ship to prevent its capture by the Flood. In 2552, Anodyne Spirit's shielding appeared impervious to even the heaviest of United Nations Space Command shipborne armaments, notably even Magnetic Accelerator Cannons.

Crew and complement
In the Forerunner era, Supernal Spiral-class keyships were operated by a crew of one princep, three navarchs, one archmedicus, and 560 adjutants. They also carried a complement of 100 Scutarii, 1,224 Strato-Sentinels, 48 s, and 890,000 Sentinels and weapon-ships.

Ships of the line

 * Anodyne Spirit — Former centerpiece of High Charity, base of operations for Dhas Bhasvod's Covenant loyalists.

Forerunner-Flood war
The Supernal Spiral-class keyship was designed by naval architects Grasping-Steady-Firmament and Lightning-Weaving-Helix, and was manufactured within the enormous production corridors of the Ingens Assembler Vats. During the Forerunner-Flood war, the Supernal Spiral-class keyship became the most established and prominently utilized class of keyship.

They were an integral part of the Lifeworkers' Conservation Measure, helping to preserve sentient life within the Milky Way. Before the firing of the Halo Array, the Forerunners used these keyships to gather specimens of sentient species located throughout the galaxy, transporting them to Installation 00 to protect them from the Flood and also the devastating effects of Halo. After the seven ringworlds fired out their pulses, many Supernal Spiral-class keyships, containing preserved specimens of each species, were sent to the planets from which the sentient species originated, releasing a population of the species on their planet of origin. Upon finishing their mission, the keyships returned to Installation 00.



Legacy
After Anodyne Spirit returned to Installation 00, a fragment of the imprisoned Mendicant Bias managed to infiltrate the vessel and attempt to use it to return to Earth where it planned to atone for its sins by assisting humanity, the Reclaimers. However, the Contender-class ancilla failed in its task, ultimately crashing on the San'Shyuum homeworld of Janjur Qom. In the following millennia, the San'Shyuum formed a religion around derelict vessel and other remnants of the Forerunners on their world. Eventually, a war was fought between two sects of the religion resulting in one of the sects boarding Anodyne Spirit and fleeing Janjur Qom. After some time, the San'Shyuum encountered the Sangheili. Their differences in beliefs regarding the Forerunners led to another war that ended in a stalemate largely the result of the keyship's extreme power and resilience in battle compared to the Sangheili vessels. Following this war, the Covenant was formed and Anodyne Spirit was decommissioned, becoming the centerpiece of High Charity, the fledgling empire's capital. There, it would power the massive space station up until the Great Schism in November 2552 when the Prophet of Truth appropriated the keyship to activate the Portal on Earth and travel to Installation 00 to activate the Halo Array. The Anodyne Spirit was left in a region of the installation known as Mahsko with a detachment of Covenant forces led by Prelate Dhas Bhasvod assigned to guard it. They dutifully remained within the keyship until the Second Ark Conflict in 2559 when a Banished raiding party infiltrated Anodyne Spirit in search of a slipspace flake. Following this, the Covenant loyalists emerged from the keyship and began to wage war against those fighting for control of Installation 00.

List of appearances

 * Halo 2
 * Halo: Uprising
 * Halo 3
 * Halo: Contact Harvest
 * Halo Legends
 * Origins
 * Halo: Evolutions
 * Wages of Sin
 * Halo: Combat Evolved Anniversary
 * Halo: Broken Circle
 * Halo 2: Anniversary
 * Halo 5: Guardians
 * Halo: Shadow of Intent
 * Halo Mythos: A Guide to the Story of Halo
 * Halo Wars 2
 * Halo: Official Spartan Field Manual
 * Halo: Shadows of Reach
 * Sacrifice
 * Halo: Divine Wind
 * Halo: The Television Series