"I can give you power, a lot of power, but every wish, every gift, comes with a price..."
Today I want to talk about one of the most useful tools in the horror GM's arsenal: The Faustian Deal. Faustian deal, named after Faust who made a deal with the devil, is a deal that gives the person a great amount of power, usually with a just as high (or even higher) price. The most common ones are usually power for the soul in the afterlife. In horror gaming, this kind of deals can be prove useful to stress the point that power carries a cost with it, and the cost is usually high.
So, how can we use it? Especially since we don't play the afterlife of the characters?
There are a few ways to use it. The first is the one that is used in Call of Cthulhu, the one of mechanical cost. Using magic, alien technology or learning about the mythos costs you SAN. It's an easy way to show the cost, as it starts a death spiral that closes on the character. It's used also in V:tR, where power cots Vitae and without Vitae the vamp starts to go frenzy. It's also not that cheap to raise it back, as it carries dangers and sometimes even humanity roles.
Another way to use it is through descriptions. You don't have to go all gross out (actually, it's better not to) but hinting at the cost, enough to excite the players' minds and you've got something. A machine that will solve the global starving problem but with the cost of a few children every day being sacrificed; A magic spell that can call the power of Cthulhu into oneself in the cost of becoming Cthulhu (after enough uses, or immediately); A gadget that can restore peace to the world (like the one used in Watchmen) with the cost of destroying a city and killing half of its population...
Another way to do it is that things don't always work as planned. I think that a perfect example for this (although a childish one) can be seen in SpongeBob, when Mr. Crab asks to speak with money and as a response has came mad. It can be seen in Buffy also, in the great episode The Wish, when with the wish of Cordelia, the consequences of Buffy not coming to town were that The Master controlled Sunnydale and the Scoobies became vamps...
How about you? How do you use Faustian Deals within the game?