Gate seal

Gate seal, also known as seal portal, was an abjuration spell used to seal a gate or portal from interplanar travel. There were both arcane and divine versions of this magic. The reversed form of this spell was known as unseal gate.

Effects
By tossing a silver trade bar at any sort of nearby magic portal, the spellcaster could permanently seal it. The silver bar would briefly transform into a silver net around the portal before dissipating.

This magic was permanent, but it could be undone, either by the will of the caster or by the use of the dispel magic spell or a chime of opening. The latter method would not function if the portal or gate was created by someone of great magical power. Either method permanently unsealed the gate. The knock spell was never sufficiently strong enough to unseal a portal bound with this spell.

Gate seal also worked to stop certain other means of teleportation, such as suppressing the magic of a stone walk effect.

A weaker arcane variety of this spell required only a steel bar, but the result was only a temporary blockage of transit. Such limited sealings revealed the sigil or the face of the wizard blocking the passage.

Components
In addition to the metal bars mentioned above, the spell required verbal and somatic components. A twig was required for the reversed form of the spell, which was snapped when the spell was cast.

Notable Users
Khelben Arunsun knew this spell and once used it to seal a portal in the Wormwrithings that led to tunnels beneath the city of Waterdeep.

The limited versions of the spell, the ones requiring only a steel bar, were commonly used on the battlefields of Acheron where they prevented foes from hopping between that plane's cubes. In such cases, the spell could be cast over the entire battlefield.

Appearances

 * Dungeon #128, "Vampires of Waterdeep: The Fireplace Level"