Taint

Some places and items are so steeped in magic that exposure to them marks, or taints, a character in a very real and difficult-to-cleanse way. Taint is dangerous. It is a corruption so deep 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 a deity, a book bound in the flesh of an archfiend for his own horrible purposes, and the presence of an evil deity are all sources of taint.