The Realm of Chaos is a strange and unfathomable alternative reality. It co-exists with our own universe, the world of physical matter, but only in a few enchanted places do the two worlds touch. One place where Chaos and the Warhammer World meet is the far north of the Old World. Here the raw power of Chaos and the physical matter of the material world intermix in a bizarre manner, twisting the landscape into strange and frightening shapes. It is impossible to be certain of the landscape in the Realm of Chaos because it changes all the time. Travellers who have wandered far north and lived to tell the tale have reported horrific visions of burning skies, of rivers of blood and plains of glass, and monsters beyond the worse nightmares of man. Worst of all are the servants of the Chaos Gods themselves - the Daemons.

There are countless types of Daemon and it would be impossible to catalogue them all. Some are numerous, but many unique. Some are huge, others no larger than a man's forefinger. Many owe no allegiance to any of the many Gods of Chaos, but the best known are the Daemons of the four Great Powers of Chaos: Khorne, Tzeentch, Nurgle and Slaanesh.

All Daemons are creatures of magic. Magic energy is the raw material of the Realm of Chaos just as physical matter is the raw material of the physical world. When they come into the physical world, Daemons can be hurt by ordinary weapons, but they are very hard to slay and it takes a brave man to face up to one of these monsters.

Daemons do not come into the Old World often. The everyday world of material things is like a barren desert to them, and they cannot survive for long outside the life-giving environment of the Realm of Chaos. It is rather like a man trying to live underwater, or a fish attempting to live on dry land.

When the power of Chaos grows strong, magical energy surges into the Warhammer World and saturates the skies with magic, enabling Daemons to pour down from the north and into the Old World. While this wave of magic power lasts armies of Chaos and hordes of Daemons threaten to overrun the lands of men and plunge the world into darkness forever.