The Communion is an alien race from the deep reaches of uncharted space. They destroyed the planet Lor-Van and threatened Earth and the rest of the civilized galaxy during the Incursion event of late 2014.
Two hundred years ago, a Lor starfaring expedition found a strange planetary body in the Perseus Arm, approximately 17,000 light years out from the star known as Sol. A surface scan indicated that the body was completely devoid of organic life, and made, right down to the mantle, of an extremely sturdy superconductive material. A few orbital drones were sent down, and the crew discovered to their great confusion that the planet had not only once been alive, but had hosted a civilization. They could find the bones of it all over - buildings, trees, highways, oceans, and beasts, all transformed into the same material. After touching one of the drones down and ensuring there was not some “gray goo” threat awaiting them, the ship landed, and a party took to the planet.
A number of theories emerged. The planet had fallen prey to a nanotech disaster, but the active nanotech had long since broken down, leaving its workings. The planet was built to serve as a living computer, not unlike some Dyson spheres in the further reaches of Lor space, and had been crafted with simulacra of a civilization as some sort of distinguishing mark. In any event, the party's engineer, an experienced technopath, attempted to make contact with the inert planet, in an effort to dig something from its database. Fifteen seconds later, the screaming started. Thirty seconds later, the planet's drones, long since left in a state of suspension, roared back to life and swept across the surface, attempting to get at the new organics who had touched down. The party barely made it off the planet with their lives, dragging the screaming technopath all the while. Once they had her quarantined, the crew's counselor attempted to parse the relevant data from the technopath. What he got was fragmented, broken, and utterly horrifying.
The planet had been organic once - once being nearly twenty thousand years ago. Two separate data banks ran in parallel through the technopath's head - one a record of the planet's history up until its transformation, one a record of victory by the thing that had done it. The entity referred to itself as “the Communion,” one singular consciousness at the heart of an endless, expansive army of drones. It had sent servants to prepare the way on the planet, subverting its orbital defenses and broadcasting messages that would “sway” the citizens to its glory. As it touched down, it broadcast a telepathic signal that brought the citizens of the planet into its fold; those that resisted were destroyed under psychic assault. After the planet was pacified, the work of conversion began. Those converted citizens who had worthwhile memories were absorbed, body and mind, into the folds of the Communion. Those who were worthless would be slain and turned into computronium, to aid the processing speed and memory capacities of the greater collective. The transformation complete, the drones would lift off, leaving the world as a relay point for the greater network and a monument to the glory of the Communion. Why would they do this? For the simple reason that the Communion believed it was the perfection of thought, and everything else was static against the void.
Once news of this got back to the Lor Security Council, a covert investigation was made into the nature of the Communion threat. If its goals were so expansionistic, then why had no one heard of it until now? A team was assembled, consisting of infiltrators, archaeologists, and top-range mentats, with the aim of prying knowledge of the Communion out of wherever it could be found. It turned out that other species and galactic entities had knowledge of the Communion; it was just buried under the auspice of legend or out of sheer loathing. The Grue Unity regarded the Communion as a mythical figure of anathema, the “Un-Thought” that bent will rather than stringing it together into a collective whole. One of The Curator's drones shared information, though at a high price, revealing how its greater self regarded the Communion as an affront to existence, something that wrecked unique entities in order to turn them into just another piece of a disturbing whole. Aside from conjecture, however, the search turned up little. The Communion had vanished from the known parts of the Milky Way millennia before.
Or so it was thought. But in late 2013, the planet in the distant reaches of the Perseus Arm - the one that clued the Lor into the existence of the Communion - showed signs of movement. As if it was booting up. It was a passing thing, and ended as soon as it had begun, but no one took it as a comforting sign.