Tainted Damage is a form of damage which cannot be removed through the normal fashion of resting and healing. It is so insidious that it must be healed by magical, supernatural, or highly specialized means. Tainted Damage is often caused by dark and destructive magic, the teeth and claws of certain legendary monsters, or cursed items and traps.
When a character suffers Tainted Damage the GM will point it out. The player should jot down somewhere obvious how much Tainted Damage the character has accrued, since those lost HP will not be recovered in the normal way. Some GMs decree that characters who die as a result of Tainted Damage cannot be resurrected, if that sort of thing is commonly practiced. Worse yet, too much Tainted Damage may cause you to rise from the grave with an unholy appetite.