In a dead magic zone, no magic, psionics, artifact, or mage-like power will function. Divine magic and constructs also do not work. Intelligent undead and other creatures subject only to magical attacks favor these areas. Most dead magic zones are created by irreparable tears in the Web of Magic.
For the deadening effect, a dead magic zone typically covers a 10d10 x 10' cubic area. The dust from dead magic zones are sometimes gathered to be used in nullifier dust. The area of effect for exploding rounds using this dust is equal to the artillery piece used to fire the round.