A dragon cast this spell onto a portal, whether a door or the entrance to a cave. The portal had to have a diameter less than 30 ft (9.1 m). Only the portal itself was warded, the surrounding wall was not. Once cast, any creature crossing the portal without uttering the proper command word became the victim of a death spell. During casting, the dragon could choose whether the spell was to radiate an aura of necromantic magic. This blue aura was visible in low-light and surrounded the perimeter of the portal.