Wyrdstone is an otherworldy stone used to make certain magical objects and structures. It is a powerful conduit for magic, and it can house creatures of the Valg realm.
Wyrdstone is smooth and black. A strong magical conduit, it can cause headaches in those with magic in their blood. Jewelry made from it can lodge Valg; donning such an item allows the Valg to possess the wearer. The size of the jewelry seems to determine what rank of Valg can inhabit it. (For example, a Wyrdstone ring can hold a lesser Valg, but a collar is capable of containing a Valg prince.) The Wyrdkeys are also hewn from Wyrdstone because of its magical conductivity.