Mordenkainen's private sanctum

Mordenkainen's private sanctum was a spell created by the famous mage Mordenkainen of Oerth that ensured privacy within a limited area.

Effects
After ten minutes of casting, this spell could create a region of privacy with a total volume of at least 150 cubic feet or greater, depending on the power of the caster. This "private sanctum" could be placed anywhere within a short distance from the caster and could be shaped to the caster's specifications. Anyone within the sanctum was protected from all scrying spells and the detection of thoughts. Anyone speaking within the sanctum could not be heard by those outside. Finally, it was impossible to see into the sanctum from outside; those trying to look in saw only a black fog, which not even darkvision could pierce.

It was still possible for those inside the sanctum to communicate with those outside if they relied on magical means, such as a sending or message spell or a telepathic link.

Within the sanctum, vision and sound functioned normally, and those inside could hear and see whatever was outside. Nothing prevented anyone from entering or exiting the private area physically.

It was possible to make a private sanctum permanent; otherwise, it lasted for a full day or until dispelled.

Components
Besides verbal and somatic components, to cast the spell required several items, all of which were consumed in the casting process:
 * a thin lead sheet,
 * a piece of dark glass,
 * a wad of cloth or cotton, and
 * powdered chrysolite.

Notable Users

 * Ebarnaje, the King of Snakes, a powerful dark naga.
 * The Faceless Incanter, a simulacrum created by Hadrhune.