Thirty-Three Chessmen, A System-Agnostic Magic Item

Thirty-Three Chessmen

Description:  Set of finely-detailed lifelike figurines made of carved and polished black or white stone, most of which wear iconic headgear that indicates their role as pawn, rook, bishop, etc.  One piece is made of gray stone and depicts a seated older man with a flowing beard, eyepatch, and wearing a hooded cloak.

Powers:  If the pieces are laid out properly on a chess board (or even just an 8 x 8 grid drawn in the dirt) the 33rd figurine will animate and grow to human size, playing with great skill against anyone who seats themselves across form him.  The Gray Player may answer questions from his opponent during the game as long as the conversation doesn't delay play, with the accuracy and breadth of his knowledge directly related to the quality of his opposite's chess skills.  If defeated, he will make a single oracular prediction (often cryptic, sometimes ominous, and always accurate) before returning to his figurine form.

The set can be used to play only one such game per day under most circumstances, but it has been known to unexpectedly activate on its own with the Gray Player offering a game to anyone he likes if the GM chooses.

Possible Origins:  It's Odin, or whatever god in your campaign most closely approaches his portfolio and personality.  The guy's as much a trickster as a ruler in many myths, and this is just one of those odd toys he likes to leave around the world to see what happens.

Complications:  If left unused for too long the set will mysteriously disappear, never to be seen again.  GM's choice as to how long "too long" is.

Also, it's Odin.  His prophecies may be accurate, but they're often doom-filled and always serve his own obscure purposes.

Design Commentary:  Reposting this from an old comment on Telecanter's Receding Blog so I don't lose it to forgetfulness.

GMs could opt to play an actual chess match to resolve the effect of the item, but unless you have a lot of time free and your players are up on the game you're probably better off using a die roll, maybe as an opposed skill check (if your rules have skills like "boardgamer" in it) or intelligence- or wisdom-based attribute test.  The One-Eyed God is a good player, but not unbeatable, and he's not above subtly throwing a game if he wants to hand out a prophecy.