One of the most impressive works of astroengineering, the Nexus-class Dominion Cipher is among the most sophisticated space-faring vessels once used by the Forerunners. Measuring nearly a thousand kilometers in length in its default-state, it overshadows most other vessels of the Ecumene Defense Fleet, including the large Fortress-class Vessels, and even with is size, its titanic engines make it capable of outrunning any fleet that appears like a vast swarm of insects. The entire hull of the Cipher is among the most formidable and impenetrable of any Forerunner vessel, being coated with a layer of a diamond-like crystalline substance capable of absorbing the most heated of pulses sent at it, and its shields are powerful enough to deflect even the strength of a massive asteroid strike: because of this, the Cipher may also act as a bunker to evade the Halo Array. Though not truly intended on being used solely as a warship, the Cipher is armed with a wide range of interior and exterior defense and support networks, including hundreds of thousands of variable Point-Defense Cannons, several hundred Particle Cannons, and thousands of internal and external Sentinel manufacturing factories capable of producing millions or even trillions of Sentinels of different classes. The main set of weapons all face forward on the ship: eight Maximus-Ion Cannons, each equivalent to around fifty Super-Heavy MAC rounds, and the Warp-Slipstream Caliber, capable of being the means of conservation or decimation to an entire planet's biosphere with a multitude of firing functions for multiple purposes. Like many other large vessels employed by the Forerunners, the Cipher is capable of converting its form's interior and exterior to adjust for its occupants and alter its appearance, but also possesses a more secondary state that acts as a massive space station designated the "Index-State".Because of its important function, only one such vessel was constructed: Ecumene's Cleric, once considered the "Galactic Index", was used by the Ecumene to function as an activation index for all installations spread across the galaxy through either physical contact or kinetic interface, capable of fully activating an installation's system or shutting them down entirely in a state of defunction: almost the Forerunner equivalent to the mythological Precursor Organon. Before the return of the Flood in the galaxy, the Cleric was employed as an index to be integrated to all Forerunner installations across the galaxy, and contain technology that could be used to secure all that the Ecumene has struggle to uphold: one such device was a Composer Sublimation Device capable of converting biological essences into digital form, which was, strangely, linked directly into the core route of the Warp-Slipstream Caliber. Eventually, the Cleric was put under the command of a Promethean prophet known as Eibon the One and All and was the flagship of a small defense fleet for the construction of Shield World X (or Homunculus), the last Shield Installation to be constructed. When the Flood made an attempt to infest Homunculus with a Mass, the Ecumene's Cleric was at the head of the defense fleet and destroyed the Flood Mass with designated targeting from the Warp-Slipstream Cannon. After containing the Flood issue, Eibon set the Cleric and the rest of the defense fleet within Homunculus' interior, placing all vessel in hibernation states until they would be discovered in the future.In 2552, the Ecumene's Cleric was a keypoint in the Battle of Homunculus between the UNSC and the Covenant, where Covenant leader Geddon 'Gunghoee sought the "Holy Cipher" to use as the key to unlock the hidden treasures hidden away in Homunculus' Boundless Asylum, and eventually took temporary control until Spartan Theron-A317 and Sangheili Affinity Officer Vanuux 'Zolurai, along with assistance from Eibon himself, retook the Cleric and used it to end the battle. After which, Eibon and his ship and dormant fleet have remained within the interior of his planet, awaiting the time when his Inheritor and the rest of the galaxy need them most, while being used as a command station for Theron and Vanuux's allies as well as one of few vessels allowed passage into the Boundless Asylum for scientific expeditions. In 2558, The Cleric gained an additional amount of defense support when a splinter faction of Promethean Knights and their commander Equinox tranlocated to Eibon and his ship, having been recently freed from enthrallment, and are now loyal to Eibon and his own allies. With so many resources, the Cleric has become a mobile domain of Forerunner achievements, especially for a key to unlocking any and all Forerunner relics spread across the galaxy.But even with all this, there are still many secrets to the Cipher that only Eibon and his Inheritor can fully comprehend.All Halo references belong to 343 IndustriesL.A.C. belongs to Nexus-class Dominion Cipher, Ecumene's Cleric and Homunculus belong to