"It is one of our Master's greatest gifts and is used in sorcery and in the making of powerful weapons....Do you wish some?"
- —Lhoigor Goldenrod, chaos sorceror and adivser to Arek Deamonclaw
A fragment of deadly Warpstone
Warpstone, also known as Wyrdstone or Witch Stone takes the appearance of a brightly emerald green crystal, a product of the solidification of pure Chaos energy. Due to Chaos being the source of all the eight Winds of Magic, Warpstone is considered by Scholars as the ultimate physical manifestation of pure magic. When Chaos first entered the Warhammer World through the two polar gates of the Old Ones, most of its energy is divided into the eight winds of magic, flowing steadily southward and eventually towards the Isles of Ulthuan where the excess magic is drained into a vortex at the center of the Inner Sea. However, some elements of the magical energys are far too powerful to be simply divided by the effects of the physical universe, and as a result, they coalesce into solid form.
A coven of Cultist surronding a Warpstone meteroite
Warpstone is therefore very rare, and can be found, smuggled, or bought into the the Old World in many different ways. Powdered Warpstone on the other hand, are sometimes drawn south from the unnatural winds of the Northern Wastes, carrying with it furious storm of wild Dark Magic that sows terror and evil on many parts of the southern realms. Most Warpstones fall to earth as meteorites from the sinister Chaos-Moon Morrslieb with the majority of the substance falling into the harsh domains of the Dark Lands. Warpstones can also be formed and crystallize from a sufficiently powerful current of Dark Magic into small pieces by very powerful Sorcerors or Magicians. Being the source of all magic, Warpstone is highly coveted by magicians, alchemists and sorcerers for its false properties of turning lead into gold and healing the sick and wounded. Most Warpstone are more commonly found in Meterorites than in any other location in the known world. Meteorites usually have a larger abundance of Warpstones than ordinary deposits, but they are sometimes irregular in shapes and sizes, and require refinement before being used for rituals or other evil-minded uses.
But to any other race within the Old World, no nation has so much great use or need of Warpstone then the great Skaven Under-Empire. The role of Warpstone in Skaven society is diverse, serving as a source of energy both for their twisted magic, advanced technology, and even as key ingredients to be used in their breeding and mutation experiments. Skavens have been known to incorporate Warpstone into piece of armor or jewelry to add a magical property to their otherwise normal gear. Warpstone has also been in use as an ingredient in magical potions or deadly poison. It has also been widely used as a form of currency within Skaven society, in the form of Warpstone Token -- a refined and minted piece of coin made entirely of pure Warpstone.
It is difficult to determine the exact physical form most Warpstones take, but many have noted that nearly all Warpstone has a black and greenish glow to them. Warpstones has also been noted to having no characteristic odor and is slightly warm to the touch. Those more unrefined Warpstones are naturally very dangerous for all creatures; prolonged exposure to the substance will lead to madness, mutation and eventual death. Prolonged consumption produces an addiction much greater than any other natural drug, an addiction that never ceases and will always plague those users for all eternity.
Source
- Warhammer Armies: Skaven (7th Edition)