Sewerm

The sewerm is a fair-sized, fast-swimming water snake of the drains under a great coastal city and the stagnant marshes of a northern coastline, such as a haunted northern marsh. Tan and brown above with a mottled green belly, it vanishes in dark water.

Its coloring grants +2 on surprise in sewers and swamps. Oil seeping from its skin numbs touch, so it often wraps a boot and leg and rides along while feeding; a surprised victim notices it only after a successful Wisdom check, rolled once a round. The same anaesthetic coats its fangs, making the bite painless, and it then drinks 1-4 hit points of blood per round. Many victims simply weaken until they drop, never feeling the snake at all. A Strength check pulls it free, the bite seals almost at once, and the oil disinfects the wound, so no disease from the filthy water can enter.

It attacks only warm-blooded prey, biting bare skin or cloth (never leather) close to the waterline, usually just above a sewer worker's boot. Since hip boots have become common, sewerms more often spend a round coiling, then launch out of the water to strike at full length, a shocking move worth +4 to surprise.

Adapted to sewers, marshes and a leech-like diet of warm blood, sewerms usually hunt alone, rarely in groups of up to six. Only newborn broods gather in larger numbers: a 4-HD mother with 5-20 young of 1/2 HD.

Sewer workers count them a deadly pest, but the city's apothecaries and physicians value them, since the numbing venom aids their work and, when prepared, lasts up to six months. Sewerms shed once a year, and the healers' guild pays 2 sp per whole skin and 5 sp per Hit Die for a dead snake (1 gp per Hit Die if alive). A local sage quietly buys them at 1 gp per Hit Die in any condition.