They come from nothing. They are madness. They destroy, corrupt, and their roots sink deep into any unfortunate world they come across. Cosmic parasites. Entropy made flesh. These gods are not your gods.
These gods are the Old Gods.
The lords of the void
In the cosmos there are certain forces at play. Two of the most primordial are those of Light and Shadow. Light emanates, it illuminates throughout all existence, and by its radiance we see all existence. It is the revelation, an evanescent force that brings other forces into existence. And such light inherently casts a Shadow.
Dwelling within that Shadow are beings of pure Void, the remnants of before existence itself. These beings do not exist as we understand it: they are a rejection of existence. They cannot exist, in the way we think of it. They are the Void Lords, dwellers in the bastion of Shadow, the last redoubt of the darkness that preceded Light. And they hate existence, the mockery of it, how it creates distinctions and boundaries and things. They hate all things, all life, all Light. They would see it all end.
These entities cannot enter our reality on their own, it is as inimical to them as they are to it. Entities such as Entropius are but the merest fragments of their colossal vastness, their cosmic nothing. But the Void Lords long ago discovered existence, and saw that it served as a cradle for vast beings of immense power. Through these beings, these world-souls, Titans were ushered into existence. And once they existed the Titans were beings of power, and that power could be turned to any purpose.
So the Void Lords strove to hurl pieces of themselves through the boundaries of creation and into existence, throughout the Great Dark Beyond. That lesser void, the black sea in which stars swim and worlds turn, was the hatchery of Titans, the nursery of world-souls. And anywhere that the fragments of the Void Lords took root, the world-souls would be battened upon by raw, primordial corruption given form. Writhing mountains of pustulent tendrils would slither through the air, would drive into the soil until they found that which they sought and slowly infested it.
The Void Lords could not corrupt an adult Titan. So they would strike them when they were not yet born. They could not know which worlds contained world-souls. So they simply hurled their manifested malevolence into the cosmos to batten upon any world it found.
The Black Empire rises
One such world was Azeroth. Possessed of a truly great world-soul, this world was unique in the cosmos, and had the potential to one day awaken into the mightiest of Titans, greater even than Aman’Thul, first of their number. The potency of the slumbering world-soul of Azeroth was so great that it drew into itself all of the elemental spirit energies that would normally sweep the surface of the world, leading the elementals into chaos and competition. Fire, Earth, Air, and Water, led by their Elemental Lords, made war on one another. They had no idea what was coming, or they might not have wasted their time battling one another.
From the sky rained horror. Four mountains of corruption dropped from the space beyond the stars and slammed into Azeroth’s surface. The greatest and most potent of these beings was Y’Shaarj, the Beast of Seven Heads, who dominated the center of Kalimdor itself. Along with C’Thun, Yogg-Saron, and N’Zoth to aid it, Y’Shaarj began the work of corrupting the dreams of the world-soul of Azeroth. If all went according to the Void Lords’ plans, then Azeroth would in time be completely covered by the corrupt offspring of the Old Gods, its dreams twisted into nightmares, and when it woke it would be a Titan unlike any other. A force of destruction and death, a Void Titan that would in time unravel all creation. This was the fate they planned for Azeroth.