Leech

Giant leeches are vile, sluglike bloodsuckers of swamp and marsh, from 2 to 5 feet in length, slimy and mottled brown, tan and sometimes gray, with two antennae on the head.

Hiding in mud, a leech attaches with its first attack and then drains 1 hit point per Hit Die each round. Its numbing saliva means a victim in water has only a 1% chance of noticing until he has lost half his hit points and feels weak. Weapons or sprinkled salt kill it. Half of all bites carry a disease fatal in 1d4+1 weeks without a cure.

Giant leeches of mixed sizes, from 1 to 4 Hit Dice, gather together in swamp and marsh waters.

This inch-long, twig-like leech hides in streams, ponds and lakes. Drinking unstrained water (gauze works) carries a 10% chance of swallowing one. It drinks 1-3 points per round for ten rounds until bloated, and each round it is lodged there the victim has a 50% chance to choke for 1d4 more damage; three straight rounds of choking kill on the third. Barring magic, only a thin heated wire or similar hot metal pushed into it bursts it safely.

A 10-foot cloud of small leeches drifts through water, draining 1d10 points of blood per round from anyone inside. Area attacks of 10 or more damage scatter it.