THE VEX
The Vex originated from before the beginning of the universe as highly tenacious patterns fleeing destruction at the battle fought outside of cause and effect. In the earliest epochs of the universe, the Vex existed as patterns in the primordial chaos, and later during the era of atomic matter rode comets down to young worlds and encoded themselves as a substrate of Radiolaria the white "milk" that is found in the centeres of almost all vex. From these primordial origins the Vex began to spread. The Vex appeared on Venus from an unknown location by way of transfer gates that allow them to instantly warp through worlds and time not unlike the eldar with their webways. All attempts to communicate with the Vex have failed, due to their single purpose to expand their species throughout the galaxy, commanded by Axis Minds that single-handedly control whole armies.
Their bodies are made of an unknown metal alloy resembling hammered brass, yet they are not entirely mechanical; some organic materials are present as well. If they are decapitated, they will remain active and become more aggressive. Their routines and ceremonies remain mysterious and illogical to humans. they are hostile, unrelenting, and deadly. The Vex despise all other races as much as humanity and are constantly fighting them across the entire universe.
why the vex have chosen to branch out into completely new universes is uknown to even those who are well versed in the inner workings of these machines.
what is known however, is that the future of the imperium, and perhaps all other races in the galaxy, including the spawns of chaos, has been put into jeapardy, and only under a united front, can these mechanical horrors be pushed back.
the indomitus crusade is in full swing, the eldar are regaining their lost strength, the orks are becoming more agitated, the necrons are returning in force, the ravenous unthinking hord of the tyranids consume all in their path and the cruel and hateful legions of chaos walk into the material universe once more.
but now, with the arrival of the vex, the universe it'self is at threat, and if this hateful galaxie's inhabitants don't unite, all will be erased by the infinite armies of the the vex.
it is the 41st millenium, and there is nothing but unending war.