The Ruinous Powers in the Mortal Realms

Chaos is not an army. It is a hunger that wears armies like clothing. In the Mortal Realms it is the oldest and most patient of all threats, a corruption that seeps from the raw stuff of magic itself and answers every mortal desire with a whispered promise. Rage, ambition, despair, delight: each is a door, and something is always waiting on the other side. To understand the Age of Sigmar you must first understand the powers that nearly ended it, for the war against Chaos is the war that defines the age.

The Nature of the Ruinous Powers

The gods of Chaos are born from emotion. In a cosmos where magic is a living force, the strongest feelings of every thinking creature drift outward and pool in a realm beyond the realms, and there they have curdled into four vast intelligences, each the sum of a single overwhelming passion. They are not worshipped into being so much as fed into being, and every act of hatred, scheming, decay, or excess makes them a fraction stronger. This is why Chaos can never be truly killed. To end it you would first have to end desire itself.

The Four Great Powers

First among the four is the Blood God, lord of war, murder, and honest brutality, whose Blades of Khorne care nothing for sorcery or subtlety and everything for the harvest of skulls taken in open battle. Opposite him in almost every way stands the Changer of the Ways, the schemer-god of sorcery, ambition, and endless mutation, whose Disciples of Tzeentch spin plots so intricate that victory and defeat blur into steps of some greater design.

Third is the Plague God, the strangest of the four, a deity of decay, pestilence, and a horrible, grandfatherly love, whose Maggotkin of Nurgle spread rot not from spite but from a genuine wish to share their gifts. And fourth, or perhaps no longer quite fourth, is the Dark Prince of pleasure and excess, whose Hedonites of Slaanesh chase every sensation past the point of ruin. This last god's fate is one of the great subplots of the setting: after the old world died, Slaanesh was hunted down and imprisoned by vengeful aelf gods, and the long struggle over that captive deity has since reshaped the destinies of entire peoples.

The Everchosen and the Faithful

Gods need hands, and Chaos finds them in mortals. The greatest of these are the Slaves to Darkness, warriors who pledge themselves not to any single power but to Chaos Undivided, seeking the favour of all four gods at once. From their ranks rises the most feared figure in the setting, the Everchosen, a champion anointed to unite the fractious hordes and lead them to final conquest. It was under such leadership that Chaos overran the realms in ages past, and the Everchosen still holds the ruined nexus at the centre of all things, a fortress-realm from which the roads to every other realm can be threatened.

Beneath the great champions swarm cultists, warlords, and the corrupted remnants of once-proud civilizations. Chaos does not only invade the realms; it grows within them, in secret shrines and whispered bargains, so that a free city may rot from the inside long before any enemy is sighted at its walls.

The Wild and the Verminous

Not all of Chaos marches in disciplined ranks. The Beasts of Chaos are its feral children, gor-kin and monstrous herds who despise every wall, road, and field that mortals raise, and who erupt from the wilderness to drag civilization back into savagery. To them Chaos is not a cause but a birthright, and they need no shrine to worship what they already are.

Then there are the Skaven, the scheming rat-men whose god has clawed his way into the Chaos pantheon, and who bring to the alliance a bottomless supply of bodies, treachery, and catastrophic invention. Between the beasts, the ratkin, and the massed warhosts of the gods, Chaos can field a horror for every kind of war, which is precisely what makes it so difficult to hold back.

The Age of Chaos

There was a time when Chaos very nearly won. In the era the histories call the Age of Chaos, the Dark Gods breached the Mortal Realms and tore down the golden civilizations that Sigmar and his pantheon had raised. Realm by realm the light went out, until only the heavens remained free and the God-King sealed his gates against the storm. For long generations, most of creation belonged to Chaos, its temples raised over the bones of the fallen, its champions carving fresh empires from the wreckage. That long night is the shadow against which the current age is measured. For the full sweep of that history, see the ages of the Mortal Realms.

The War Without End

When the Stormcast Eternals fell from the sky and the Age of Sigmar began, Chaos was not destroyed. It was merely denied its total victory, driven back from some realms and forced to fight for what it had once held uncontested. That is the honest truth of the setting: Chaos cannot be beaten, only resisted, because it is woven into the fabric of a universe that runs on feeling. Every triumph of Order is temporary, every reconquered city a wound that may fester again. To grasp why the realms are worth defending in spite of all this, begin with What Is Age of Sigmar?, and then look to the horizon, where the storm clouds are always, patiently, gathering.