A painful but powerful ritual, and a fiendish trap.
Ritual Components: This ritual only works if the person who taught it to you is still alive. Place an ordinary metal pin in the urinal of a public restroom on the day of a full moon. On the day of the next full moon, retrieve the now-unpleasantly rusty pin – if it’s been cleaned up or flushed away, the ritual fails. Pierce your ear with the pin – unfortunately, it’s almost certain to get infected. Before removing the pin from your ear, tell a child a story about the end of the world. Any story will do, as long as you make up the story. The child must then give you a piece of paper. Write a wish on the paper, which no one else knows, then pull the pin from your ear, and use the pin to stick the paper to your clothes.
Effect: So long as you wear the pin on your clothes, no one in the building where you placed the pin will be able to perceive you in any way. You could be shouting at them and strangling them, and they’d only know that they couldn’t breath. You can take it off and stick it to another set of clothes, if you like, too. However, whenever you wear the pin inside the building, you’ll have a terrible headache. After you’ve used this ritual successfully, you can’t use it again.
Horrific Side Effect: The headaches get worse and worse as you use the pin: for every 10 minutes you spend in the building, wearing the pin, you get a -1% to all rolls from the pain. When the penalty reaches -30% (that is, after five hours spent inside the building), the pain goes away completely, but the pin loses all magical power. You’ll feel a swelling in your head, though, and an X-ray will show that there’s now an embryonic snake curled around the base of your brainstem. About a week after the pain ends, the snake will hatch, splitting your skull open and killing you instantly. However, you immediately become a demon familiar, bound into the body of the snake that split your skull and devoted to serving whoever taught you the ritual. Use all normal rules for demonic familiars. Your new Obsession is based on whatever you wrote down in your wish.
Weird icky and cool. Kinda fucked up thing to spring on your players though
Question, does the serpent appear if you use the pin for five hours, or if the pin is used at all? So if a character were to use it for three hours whilst hacking into the FBI mainframe (or whatever) and then left, would he get the snake or not? If not, I can see the person teaching someone the ritual “forgetting” one important bit about the whole thing… Ooooh very nasty.
You don’t get the serpent until you use the pin for a total of five hours. So if you use it for three hours, you’ve got horrible headaches while you’re inside the building, but you’re otherwise fine. If you use it again years later, and use it for two more hours, then the serpent will appear.
Yeah, I assume that most people who learn the whole ritual won’t use it themselves – they’ll teach it to someone else and forget to mention the “eternal servant” part.