Obsidian is a black stone born of volcanic fire that is the material bane of magic, which it can refract, weaken and even completely negate in certain circumstances. In places layered with the stone such as the Obsidian Hall of Altdorf, wizards can feel their power dimmed by the presence of so much of the substance all around them.[1a]
It takes an artisan to carve and fashion obsidian. Dark Elves are the true masters of this art, although others have produced fine pieces too.[2a] Items, such as talismans, made from obsidian often hold arcane power, and so those skilled in its manufacture are widely sought. To be skilled at carving obsidian is to be skilled in sigils and symbols of power, for obsidian soaks in the power of the ensorcelled.[2c]
In Norsca, obsidian is one of the most prized materials for use in armour-making. Although few Chaos Marauders are lucky enough to have it, it is thought that many Chaos Champions wear such armour for its bulky, sinister appearance, striking fear into the hearts of individuals who face them. Obsidian is almost always used in full suits of armour due to its bulky nature, which may cause the user a disadvantage if they do not have the strength to bear such a suit. This potential disadvantage makes obsidian impractical to use without that essential intimidation factor.[2b]
Obsidian is also highly desirable for Norscan weapon-making, being much harder than other materials but more malleable in the forge.[2b]