From the publisher:
Some places and items are so evil or filled with Chaos that exposure to them marks a character in a very real and difficult-to-cleanse way. Taint is evil. It is a corruption so deep that it warps the very plane of reality. A weapon used to slaughter thousands of innocents, a forest grown on land soaked in the blood of an evil deity, or a book bound in the flesh of an archfiend for his own horrible purposes, are all sources of taint. Taint makes evil a physical threat to the well-being of characters and can have a lasting impact on characters, even killing those who remain exposed too long.
Sanity is the natural mental state of ordinary life. Normal mental balance is endangered when characters confront horrors, entities, or activities that are shocking, unnatural, and bewildering. As a character encounters monsters, witnesses horrible acts, masters forbidden knowledge, or casts spells, his Sanity score, and his corresponding ability to function as a normal character, deteriorates. Soon, all that is left is a gibbering madman.
This 28 page supplement contains all the rules that GM's and Players need to add Taint and Sanity to their RuneQuest games.
Requires the use of the RuneQuest(TM) Main Rulebook available from Mongoose Publishing.