Magical Chessmen of Ultham-Urre

The Magical Chessmen of Ultham-Urre were a set of chess pieces and magical artifacts created by the archmage Ultham, son of Urrekanam, of Chessenta in the 10 or early 11 centuries DR.

Description
The Magical Chessmen of Ultham-Urre comprised a full set of thirty-two chess pieces. They were made from luspeel (magnetite), so they would have a slight magnetic attraction to a steel chessboard. Each piece was carved to resemble a Chessentan citizen, with lifelike appearance and every one unique. Their heights varied according to their strength, from for pawns to  for kings and queens. The red set was inlaid with small jacinths and the green set with small beljurils.

Powers
Each of the Chessmen had a variety of strange magical powers. First, each of the red set functioned as a ring of fire resistance and each of the green set functioned as a ring of lightning resistance. This was a constant effect, provided it was held in a bearer's fist. For their other powers, the Chessmen had two command words, and these were the same two for every piece. To use these powers, the bearer needed to invoke one of command words and concentrate for a full minute without interruption, like with spellcasting.

First Command Word
Second, a Chessman (bar the rooks) could transform a bearer (human, demihuman, or humanoid) into a hero of a nature and strength according to the color and rank of the chess piece, essentially becoming the figure it depicted. In the red set, pawns made lowly thieves, knights made mid-level fighters, bishops made mid-level clerics, kings made high-level fighters, and queens made high-level mages. In the green set, pawns made minor fighters, knights made mid-level rangers, bishops made mid-level druids, kings made high-level rangers and queens made high-level mages; bearers of the green set were required to follow the codes of behavior of their hero whilst transformed.

To use this power, the piece must be held in the bearer's fist and the first command word invoked. The piece vanished and the bearer was transformed, losing their own special skills, weapon proficiencies, and spellcasting ability, while gaining those of an adventurer of the appropriate kind, though their options were fixed. They stayed transformed until an hour had passed, they said the first command word again, or they died. A different Chessman could not be used whilst transformed. When it was undone, the bearer became as they were, the chess piece in their hand, and their body restored of any injuries with a heal spell. The piece could not be used again until 24 hours had passed.

Meanwhile, when used in the same way, a rook piece would turn into a small fortress, rather like a Daern's instant fortress. This lasted indefinitely, only turning back when the bearer said the first command word again, and the rook piece reappeared in their hand. All damage sustained by the fortress was repaired between these transformations.

Second Command Word
Third, each Chessman had within it an extradimensional space similar to a bag of holding. Pawns were equivalent to smaller bags of holding, while all pieces were equivalent to the largest bags of holding. Unlike a bag of holding, it was impossible to put a Chessman into another extradimensional space (like a bag of holding or a portable hole) or put one into a Chessman, and a Chessman could not be put inside another.

To use this power, the bearer must hold a Chessman, touch a non-living object to it, and then invoke the second command word, whereupon the object was disappear inside. If it was full, nothing would happen. To take things out again, the bearer must hold the Chessman without any object touching it, and then invoke the second command word, whereupon a random object inside would appear nearby by. Thus, recovering a specific object could be time-consuming if many others were kept inside. However, if it was empty, then a random object nearby would go inside instead.

Originally, Ultham stocked the pieces with supplies: water, non-perishable food, armor, weapons, equipment, and spell components. These were appropriate to each chess piece and transformed hero, and some was thought to be magical itself. In any case, most sages expect that, with later owners and centuries of use, most or all of these original supplies would've been removed or lost and that by the mid-1300s DR, they would hold just about anything, or even nothing. This could even be quite hazardous for an unlucky storage hunter.

Loss
While not actually cursed, the Chessmen were incredibly hard to keep in one's possession because of a strange magically quasi-magnetic property of the enchanted luspeel that saw them attracted and teleported to large pieces of enchanted steel, such as a magical sword, shield, or suit of armor. If a bearer of a Chessman had a piece of magical steel in their possession, the Chessman would become attuned to it in three or four days, and ignore it from then on. However, if the bearer passed somebody else with a piece of magical steel of their own, one the Chessman had not been in the vicinity of previously, there was a one-in-a-hundred chance the Chessman would teleport across and appear nearby, such as in a backpack or pouch. If the passerby already had a Chessman of their own, nothing would happen.

If there were multiple Chessman in the bearer's possession, then each had the same chance of teleporting away. However, rather than being separated long-term and scattered across the land, the Chessmen would follow each other. Every hour after the first to teleport, another random piece would teleport to that lucky passer-by until they had the full set in their possession.

No physical barrier or magical safeguard could prevent them teleporting. Inorganic, non-magical objects attached to a Chessman (by being tied to, strapped on, or wrapped around) could be taken along as well. However, living things and magical items were never taken.

History
Although the facts are lost to history, sages theorized that, sometime during the reign of King Tchazzar (929–1018 DR), Ultham predicted Chessenta's swift collapse and subsequent incessant warring. Thus, using rare minerals and gems found in the Hills of Maerth where he dwelled, he created the Magical Chessmen of Ultham-Urre to defend the nearby village of Oslin he was so fond of and to protect his friends there whom he'd spent many hours playing chess with. Before he journeyed into the planes, he left the Chessmen in Oslin, where for several years they were just used as simple chess pieces.

Then, several years later, the lord of Maerduuth (at the time a large city) desired to annex Oslin and sent an expeditionary force, thinking it defenseless. But the farmers, fishers, and traders of Oslin used the Chessmen to transform themselves into a company of strong soldiers, supported by potent mages and priests, that routed the Maerduuth force. A second expeditionary force didn't come back at all. Thereafter, the lord of Maerduuth and the neighboring powers elected to just ignore Oslin altogether.

Curiously, several decades later, a well-defended caravan transporting a fortune in gems from Unthalass to Akanax disappeared between Oslin and Maerduuth. The lone survivor reported they'd been ambushed by a company of glittering, armored knights—most likely the Chessmen again—and investigators found Oslin emptied of half its population overnight. They, the gems, and the Magical Chessmen of Ultham-Urre were not seen again. Thereafter, Oslin relied on mercenaries for protection.

While there were no reports of any of the Chessmen being found or identified since then, several rumors had them appearing all around Faerûn. Just locating them, let alone determining their command words, was expected to take a quest for countless bits of obscure information. The adventurer Wilund tried to find them, and gave The Alcaister, an antique spellbook, to the sage Ardagundus of Baldur's Gate in exchange for information on their functions and whereabouts; it is unknown if Wilund succeeded or not. One tale held that a lady member of the Company of Crazed Venturers boldly escaped from a noble's mansion with the aid of the Chessmen; however, this lacked evidence and was likely false.

Destruction
Should it be necessary, there were two ways proposed to destroyed the Magical Chessmen of Ultham-Urre. The first was to animate them and have them battle each other in a live chess game between the gods Torm and the Red Knight. The other was to have tanar'ri demons use the red set and baatezu devils the green and fight a battle of the Blood War. In either case, regardless of who won (unless it was a stalemate) the whole set would disappear forever.