"In the ages of our Covenant, we came to call these god-machines "Arlyvrs", after ancient judge-demons that guarded the gates of eternity. It was fitting; only the most honourable could defeat their challenge and inherit the divine treasures the Forerunners left behind."
The Z-8130 Automated Fleet Deterrence Drone, colloquially known as the Devastator Sentinel, is the largest and most powerful sentinel variant encountered by the UNSC and Covenant. With their manufacturing facilities discovered above the Halo fortress-worlds and certain shield worlds, Devastator Sentinels are weapons of last resort and are thus only distantly related to the far smaller automatons they are deployed alongside. Equipped with weaponry so powerful that it would put most warships to shame, they are built to remove all Flood and foreign invasions regardless of damage done to the megastructures they are built to protect. As a result, these Sentinels are deployed only when all other containment protocols have failed and the Flood's efforts to form a planet-encompassing key mind are almost inevitable.
Like all other Sentinels encountered, Devastators are built with a focus on ease-of-construction and resilience. As a result, while the technologies used are more advanced then the equivalents used by any contemporary race, they are cruder and less efficient then those used on dedicated Forerunner warships. For example, Devastator Sentinels do not have a distinct reactor; instead, the engine chambers used to provide propulsion are also used to recharge and focus its main guns in addition to power generation. The hull is built from readily-available elements found in their system, and is vastly inferior to the alloys found even on the installation itself. In fact, only the Sentinel's engines are comparable to the standard welded by the Forerunners at their height, and this grants it unnatural speed and agility for a ship of its size.
Recovered records from Forerunner terminals have revealed that the Devastator Sentinel was not a new design by the time of the Flood's invasion on the galaxy, having evolved from a spatial mining bot used by the Minerrate. Deployed alongside Strato-Sentinels, these failed in a bid to cleanse the worlds visited by the parasite, proving to be poorly-suited against the reterraforming properties of the spores. Steadily upgraded throughout the war, Devastator Sentinels would become one of the most numerous weapons the Ecumene had at its disposal. In spite of it, the Flood continued to advance and production could never keep up with the losses inflicted in the field. Once the Halos were activated, these sentinels were deactivated and shut down, or scuttled to help repair the damage taken during the war.
↑While the Sentinel Devastator does not have a slipspace drive, it has been observed for the sentinels to utilise the translocation arrays within the installations they are stationed at to pursue fleeing targets. Unfortunately, this method is a one-way trip; Devastators are unable to return at faster-then-light speeds.