Parasite

A parasite lives in or on another creature and takes nourishment while giving back little or nothing. Ordinary ones are mostly pests, though they occasionally lead to complications, and casting cure disease wipes them out without trouble. The varieties below are less common.

A tiny metal-skinned worm with four eyes like little red gems, the bloodring curls into a loop and lies in wait, hoping some thinking creature will slip it on as jewelry. Worn, it sips a single point of blood hourly, never more than 6 points in a day. Most of that energy fuels its magic resistance, and the wearer enjoys half that resistance too. Kept well fed, the worm lengthens by an inch weekly, up to a full foot.

This small insect normally lives in wood, eating dead cellulose, but it needs warmth for its eggs and favors human or humanoid ears. An adult crawls inside, deposits 1d8+8 minute eggs, then creeps back out to die. Nothing is felt until hatching, 4d6 hours on, which brings a faint tingle. The larvae then burrow into the flesh, generally heading inward, a painful process costing 1d4 hit points every round until the host is dead. Cure disease destroys the brood at either stage, though it heals none of the harm already done.

A flat, round beetle whose golden, contoured shell passes for a gold coin. Everything it sees and walks with sits on the underside, and folded up, even that face resembles a strangely struck coin. Half of all inspections fail to spot the fake unless magic is used or the handler, say, bites it to test the metal. Goldbugs rest in clusters with their own kind, or among genuine coins, until somebody scoops them up.

Once its new owner sleeps, the goldbug bites and drinks. The bite lands automatically on a sleeper, who has just a 10% chance to wake, and the bug drinks 1d3 points per round until it has swallowed as much as its own full hit point total. It can fast for long stretches but prefers a daily meal. Threatened, it bites in earnest for 1d4, and the venom calls for a saving throw against type F poison, made with a +3 bonus.

Hard to spot and harmless-looking, these lice spread by jumping from one host to the next. A few do no harm, but give them a week and they multiply into a colony big enough to feed on what they really crave: spells. Once they settle on a spellcaster, or merely in a caster's robes, one prepared spell vanishes from memory daily, chosen randomly. A plain bath does nothing; harsh soap or another potent cleanser kills them, and so does cure disease.

Looking like a loose scrap of skin, the flat vilirij flies after dark in search of hosts, often clinging over a doorway or to the ceiling, then drops onto bare skin, ideally somewhere rarely seen, and sticks fast. Its anesthetic venom numbs the spot and clouds the host's mind so the victim never notices it, while everyone else sees only a discolored patch. Every day it drinks 1d4 points of blood, continuing until someone peels it off. Anyone who has met one before recognizes it at once.