Door of AlarmLevel 2 Uncommon

This seemingly innocuous door issues a shrill alarm when an unknown creature walks through it.

Wondrous Item        520 gp

Property

You can spend 1 minute to attune any number of individuals to this door. When a creature other than an attuned individual walks through the door, a shrill alarm sounds and doesn't stop for 1 hour, until that creature leaves through the door, or you command the door to be silent.

Published in Adventurer's Vault 2, page(s) 80.