Here is an unfinished article I was working on a while back. Something interesting to drop into the possession of the PC's in a KULT game. While I never finished stating it completely out you pretty much get the full idea here. The chances of me ever finishing it are slim to none so I might as well share what I have so far.
For years these little artifacts have been circulating among cults and subversive societies. Small black squares that defy ones own eyes and are said to provide visions, supernatural abilities and even extend the lives of those who possess them. You can find them by following the trails of murders, sacrifices and death that always seem to occur whenever they are around. Either by those who claim to control their powers, or by those who seek them.
These tiles are square, three inches long on all sides and a quarter inch thick. They feel heavier than any normal stone tile by about double the weight. Visually they normally appear as a flat black but when looked at from various views they change from a shiny finish, to marbleized with red streaks, to a static gray and even to a slightly transparent smoke color.
First and foremost they erode the mental balance of anyone who stays near them for any extended period of time. The rate of loss is around one point per week if it stays within their nearby vicinity, or by one a day if they carry it on their person. Negative mental traits are picked up, usually in the psychopathic variety. The desire to cause harm and suffering to others grows steadily within them.
Any user of the Lore of Death receives a bonus to their skill level whenever it is included as a center piece to any of their rituals.
After and hour or so around the tile people with an already low mental balance will start to hear voices. Usually the sounds of people crying out in pain, begging to be killed and lots of sobbing and screaming.
Someone with a mental balance higher than a positive 50 feels uncomfortable at the site of them. Getting headaches, nosebleeds and nausea the longer they stay around one.
In actual reality these tiles are stolen from Inferno by a Nepharite years ago. Removed from the floor of a torture chamber in an abandoned citadel. Some unknown deal was made with a Lictor who brought them over into the illusion for their own nefarious uses.