The Demon's Advantage

Disclaimer: The item is form the short story 'A Night in the Tropics' by Jeffrey Ford.
Full Item Description
A chess set crafted by Foresso, the apprentice of Benvento Celini, one of the greatest goldsmiths that ever lived, for Isiaso. Crafted to represent the eternal struggle between good and evil, the pieces are solid gold, beautifully crafted, in the images of the saints and demons. And, if you look closely, you can even see the holes in the Crist's hands.
History
Isiaso was the son of a Spanish accountant, and a native of Hispaniola. His mother was supposed to have been descendent of a long line of sorceresses, an adapt of the magic of the islands. Isiaso, a veritiable genius learned from both of his parents, and when he turned 20 his father shipped him off to Rome to finish his education. It was here that he mingled with many of the great philosophers and theologians of his time, and started viewing the struggle between good and evil as a chess game, with the advantage going from side to side.
While he was in Rome, he rose in power quickly, far too quickly, and no one could understood where his money came from, or why anyone who crossed him meet with weird and untimely deaths. Soon he has enough money to commission Foresso to make the set. And he got his money's worth out of it too.
Enter the Pope, John III, a great patron of the arts. He hears about this incredible chess set being crafted by Foresso and goes to see it himself. Soon Isiaso is getting called upon by one of the Pope's underlings, who tells him that the Pope wants to buy the piece off of him. And Isiaso accepts, under the conditions that he be provided passage home, and that he'd be given a position as a professor at the university that was being planned in Santo Domingo.
Now the Pope accepts, over-joyed that Isiaso would ask for this. You see, the Vatican had been planning to see that Isiaso would get shipped off elsewhere, seeing him as a troublemaker and a savage.
So, on the trip home, the ship stops off of some uninhabited island, and Isiaso is asked if he wants to see 'Paradise on Earth.' Isiaso, being a curious man, agreed, and they went out to the island. Halfway through his 'tour' he notices that his guide isn't there anymore. He hurries back to shore, only to find that the ship is pulling up anchor and heading out. You see, the Vatican wanted him out of Rome, but was to afraid of his 'magic' to boot him out. It had been their plan from when he asked to go home to strand him on an island in the middle of nowhere.
From there the chess set more or less disappears from recorded history, there are legends of course, dark legends. They say that while he was alone on that island Isiaso cursed the chess set. The legends also have it that, as long as you play the demon side of the board you can never lose. And, similarly, that you will be prosperous in whatever business dealings that you make, as long as others suffer because of it. Some of the richest men were rumored to have owned this, but whether or not it is true will remain a mystery. The curse though, is that whoever owns this chess set has no chance of peace, and no hope of peace in any life after this one, whether it be heaven or achieving Nirvana, they will never be able to achieve it.
Magic/Cursed Properties
You can never lose when you play the demon side of the board, conversely, you will always lose when playing the saint side of the board. Similarly, in business dealings, any deal that would cause others to suffer, the more pain it causes the better, you will at least achieve a degree of success, but any altruistic act will be doomed to failure, and events will seem to unfold that cast that act in the worst possible light.
Whoever owns this chess set has no chance of peace, in this life or the next. They will suffer from mild maladies for the rest of their lives, things that caused happiness before will seem dull and boring. They will suffer from a sever case of ennui, a never-ending depression. They will be plauged by insomnia, not horrible insomnia, but bad enough that they will suffer from it.
If they die with this in their possession they will never see Heaven/Walhalla/Nirvana, ever. They'll have nothing to look forward to for all eternity besides pain and suffering.
They can't just give it away or sell it. If they do they'll be free of the aforementioned curses/charms for a week or two, but then they'll start having horrible dreams. And bad stuff will start happening to them/those they love. Their mother will die of some terrible wasting disease, they'll break all the bones in their body. But in all of this, they won't die, but they will be driven slowly insane by the dreams, which will get worse, until they can't tell days from months, and everything merges together into one, unending nightmare. Until they get it back, at which point anything that can get better will.
The chess set can only be taken from them, and when it's taken, violence must happen. Blood must be drawn, from everyone involved in the theft.
Plot Hooks
Steal It, Please - You get hired by someone to steal a solid gold chess set from this vile, wealthy merchant/baron. Everything goes well in the theft, until you find the owner sitting up, playing a game of chess with himself. When told to hand over the game he does so, willingly in fact. But as your party is leaving he draws a knife and starts attacking your party.
Steal It, Please II - You hear rumors of an extremely valuable chess set, in the possession of a wealthy, but vile, merchant/noble. When you get there the guy is sitting up playing himself in a game of chess. He tells you that you can have the chess set, under the condition that one of you has to hold it while everyone else gets their palms cut by the merchant, who promptly cuts his guts out after he cuts everyone's palms.