An Attack Moon was the Imperial designation given to a class of massive Ork vessels that were encountered by the Imperium of Man during the War of the Beast from 544-546.M32. These massive voidcraft served as the flagships of the group of massive Ork Warlords who each were known as The Beast. They were capable of almost instantaneous travel through a hyperdimensional realm known as "subspace" and were outfitted with a powerful gravitic weapon capable of ripping apart even the largest of Battleships or even other planets.
Ork Attack Moons, like the much smaller Roks, were constructed from a core that included the hollowed-out remains of large asteroids and small planetoids or moons. At the height of The Beast's reign of terror in the mid-32nd Millennium, the Orks were capable of using technology that surpassed even that available to the Imperium of Man. The Attack Moons were capable of Faster-Than-Light travel over large distances without the use of the Warp, which mad possible instantaneous interstellar travel for Ork forces from one location to another, and were outfitted with immensely powerful gravity-based weapons capable of destroying entire planets.
The hollowed-out moons were covered in a vast pattern of fused wreckage and interconnected metal plates, thick enough that kinetic or directed energy attacks against the moon's surface were completely ineffective. The Attack Moon's most obvious external surface feature was that of adjustable plating capable of moving, shutters the size of inland seas and raised portions the size of entire mountain ranges that were capable of forming the stylised image of an Ork face, and could move in time with the words spoken by the Great Beast. The vast and monstrous tusked maw could stretch open wide, allowing Ork warships and transports to travel outwards from the core of the Attack Moon. The eyes burned with the magmatic light of the moon's core.
An Attack Moon was capable of appearing through subspace closer to a planet than the laws of physics allowed, causing immense destruction upon the world it visited as its gravity field was completely disrupted by the tidal forces generated by the sudden arrival of the massive Ork planetoid. When an Attack Moon appeared over a target world, it emerged from subspace close enough that the sound from its titanic, Ork-shaped maw was capable of travelling to the planet's surface, heralding the arrival of the Great Beast.
Attack Moons were capable of FTL travel through the creation of what were known to the Adeptus Mechanicus as "subspace" corridors, a hyperdimensional realm that existed "in-between" the Materium and the Immaterium. A safer method of travel than through the Warp, subspace travel none-the-less was not entirely instantaneous and did require some travel time, with the arrival of the Attack Moon at its destination in realspace heralded by strange gravitational phenomenon, culminating with the moon flickering in and out of existence until it fully materialised. While transitioning from one planet to another the receiving planet would be subjected to greater and greater gravitational stress, resulting in sudden climate change, earthquakes and other geological catastrophes. Once the Attack Moon arrived in-system, usually impossibly close to its target, the moon would disgorge an endless stream of warships to protect the moon and assault craft to begin planetary invasion. Once a world was completely under the control of the Orks, a special gravitic nexus facility would be constructed on the planet's surface, a match to an existing facility on-board the moon. Once constructed and activated, the gravitic nexus would begin the slow process of tearing the planet apart, with massive chunks the size of mountains being lifted into the maw of the Attack Moon, to become part of the moon itself.
The Attack Moons of the Great Beast were not just simply massive transport vessels or war-machines, but instead they were rather nothing than advanced prototypes, as the Orks sought to perfect their gravitic planetoid concept. The perfected method, known as an "Attack Planet", was to be finished at Ullanor, and was intended to attack Terra itself while using the smaller Attack Moons as mere beacons for its travel. The Orks built an unknown number of Attack Moons during the War of the Beast, with several being destroyed by Imperial Forces during the war at great cost. Imperial Records do not indicate what became of the remaining Attack Moons after the Orks' ultimate defeat at the Third Battle of Ullanor, although it is believed that those that remained were hunted down and destroyed by Imperial forces or were abandoned.
In addition to the Attack Moon's ability to destroy a world by merely translating too near the planet, and its immense tractor beams capable of tearing the planet to pieces, the Attack Moon boasted a considerable arsenal of surface weapons and powerful Void Shields. The Attack Moon's main weapon was known as a "Gravitic Whip," a massively powerful gravity weapon that took the form of a green tentacle-like whip that would strike out towards its target and either tear it apart near instantaneously or wrap around and crush it. The weapon drew upon the great Ork energy sources buried deep within the vessel, and could be seen visibly charging for attack as coils of green energy coruscated up the pylons that directed the flow of energy to its target. The Gravity Whips were capable of fending off entire fleets on their own, with each flail of the whip tearing apart Cruisers with ease, destroying entire wings of Attack Craft and causing untold destruction against larger ships. Fortunately for the Imperium the weapons required massive amounts of energy and needed to recharge between attacks, which gave Imperial Battlefleets enough time to close and engage the moon.
- Warhammer 40,000: Rulebook (6th Edition), pp. 169, 201
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