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.

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.

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. He even included inside the pieces with supplies: water, non-perishable food, armor, weapons, equipment, spell components. 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.