When an alarm spell is cast, the wizard causes a selected area to react to the presence of any creature SIZ 1 or larger. The area of effect can be a portal, a section of floor, stairs, etc. As soon as any creature enters the warded area, touches it, or otherwise contacts it without speaking a password established by the caster, the alarm spell lets out a loud ringing that can be heard clearly within a 60-foot radius.
The sound lasts for one minute and then ceases. Ethereal or astrally projected creatures do not trigger an alarm, but flying or levitating creatures, invisible creatures, or incorporeal or gaseous creatures do. The caster can dismiss the alarm with a single word.