Daern's instant fortress

Daern's instant fortress, commonly known as an instant fortress, was a type of magic item that allowed the owner to summon a nigh-impregnable fortress made of adamantine.

Description
When inactive, a Daern's instant fortress appeared to be a small cube    made of iron streaked with rust that was  on each side.

Powers
By placing the cube on the ground and speaking a command word, the instant fortress rapidly grew from a small cube into a square fortress  on each side with adamantine walls that were  high    and which extended a further  into the ground,    thus making the fortress very sturdy even before the enchantment ensuring that it was impossible to tip over. The walls all had arrow slits   and were topped with either crenellated, machicolated,  or closed battlements. The enchanted adamantine structure was resistant to most forms of magical damage and was impervious to attacks by normal weapons, although it could be damaged by catapults or other siege weapons. An instant fortress could not be repaired by any normal means, and accumulated damage had to be removed with wish   or miracle spells (which could only repair some of the fortress per casting,   thus requiring the caster to specify which part of the fortress they intended to repair).

The rapid growth of an instant fortress&mdash;with one reaching full size in anywhere between six and sixty  seconds&mdash;posed an imminent danger to those nearby of being crushed,    although in most cases the owner of the instant fortress did not need to fear such a fate. For all intents and purposes, an instant fortress was a permanent structure once activated, and could only be returned to its small metal cube state by using a command word to dismiss it from the outside. This command was usually different than the word used to activate it in the first place, and would not work unless the fortress was empty.

The interior of the instant fortress was accessible through a small door that always appeared on the wall facing the item's owner when the fortress arose. This door could only be opened or closed at the command of the item's owner, and even knock spells or other means of magical unlocking&mdash;such as a chime of opening&mdash;could not cause the door to budge. The interior itself had two floors connected by a ladder, which also extended all the way to a trap door offering access to the battlements on the roof. It included sleeping and living quarters for up to twenty occupants, however it did not include any food or water. The fortress was not waterproof, did not provide its own breathable air, and was not insulated, meaning that aside from blocking out the wind, it was the same temperature inside as outside.

History
Beginning in the early-to-mid 14 century DR, a functionally permanent Daern's instant fortress was erected in a low cavern in the Northdark northwest of Blingdenstone. This place was known as Fendlestick's Folly, named for the human wizard who chose the ill-fitting place for his fortress before being killed and taking the command words with him.

As of the mid-to-late 14 century DR, crafting an instant fortress required access to the spell Mordenkainen's magnificent mansion.

The properties of a Daern's instant fortress changed somewhat during the era of the Spellplague. For example, it could only be activated once per day, and it would refuse to grow to full size if it there were obstacles in its intended footprint. It could also be dismissed while people were inside of it, and they would be harmlessly shunted out of the fortress as it shrunk. In addition, the walls were said to be even more invincible; however, the small door was less secure and could be forced open. Following the Second Sundering, the properties were once again the same as they had been prior to the Spellplague.

In the late 15 century DR, a wizard erected an instant fortress within a region of the Northdark known as the Labyrinth, but she was subsequently slain by shadow demons. Her demon-haunted fortress came to be known as the Adamantine Tower.

Reputation
Daern's instant fortress was a rare item that was particularly valued by adventurers and the like who traveled in dangerous environs. It could easily withstand hurricane- or tornado-force winds.

The ancient Netherese fortressmantle was an enchanted cloak that could create a structure similar to a double-strength Daern's instant fortress by pulling the hood over one's head.

The powers of the rook from the Magical Chessmen of Ultham-Urre were the same as those of an instant fortress, except that it could repair itself between uses.

The archdevil Malphas of Avernus was innately able to summon a temporary fortress similar to a Daern's instant fortress, except that the door was not beholden to only his command.

Notable Owners

 * Brister Fendlestick, who erected his instant fortress in the Underdark and was killed in the early-to-mid 14 century DR.
 * Jarlaxle, the leader of Bregan D'aerthe, possessed a special form of instant fortress, known as Caer Gromph, which resembled a giant stalagmite and which could be shrunk to its portable cube form with soldiers hidden inside of it.
 * Joppa, an Oerthian monk active around Waterdeep in the late 15 century DR.
 * Kardhel Terov, a Warlock Knight of Vaasa in the late 15 century DR.
 * The Doomguard of Sigil were said to use Daern's instant fortresses when traveling to the Abyss, such as in Twelvetrees.

Background
The instant fortress is evidently named for a hero and goddess from the Greyhawk setting who has no official connections to the Forgotten Realms. For more information on her, see Daern on the Greyhawk wiki.

Appearances

 * Adventures
 * Out of the Abyss
 * Novels
 * Exile &bull; Blades of the Moonsea (Swordmage, Corsair, Avenger) &bull; The Last Threshold
 * Night of the Hunter
 * Video Games
 * Warriors of Waterdeep
 * Warriors of Waterdeep