Helm Leech

From outside a helm leech looks like a hard shell up to a foot tall, much like the barnacle-stage young of void krakens, tinted to match the hull it clings to so that casual inspection seldom notices it. Inside lives a reddish-purple, snaillike body with one watery eye at one end and a foot-long tentacle of the same color and texture, studded with sharp spikes.

Usually the tentacle is enough: its spikes deal 1d4 damage, which convinces most creatures to leave the parasite alone. When that fails, it turns to magic.

Lodged near the starhelm, the leech feeds on whichever priest or wizard is driving the vessel, absorbing one random spell of any level from the caster's mind for every ten days of flight, so a 30-day voyage gives it three. It can store only four at once, but every leech aboard steals separately. The victim forgets each stolen spell and must regain it normally, yet does not notice the loss until trying to recall it.

Attacked, the leech fires off its stored spells at random, one per round, until none remain. Each is cast at the level of the caster it was taken from, or the average level if several people ran the helm during that ten-day stretch. It will do this against any physical blow, often when its area of hull is pounded in a battle, which sometimes helps the ship and more often wrecks it.

Only two tactics work well against a charged leech: kill it in one blow, or neutralize each one with its own dispel magic before attacking. Its 25% magic resistance makes either approach uncertain. Once its spells are spent and its shell is broken, it is easy prey.

Needing no air, leeches turn up wherever starships travel, through the void between worlds and the flame-sea alike, drawn without knowing it to the casters who power them. A drifting spore settles on the hull near the starhelm, bores in, and eats away 1 hull point of the ship each month. Within a week it grows a hard shell colored roughly like the hull and cements itself in place with a tough glue, so scraping it off is slow, tiresome work.

They occur in groups of up to four. Any group of three or more has a 10% chance of including a mated pair that releases 1d6 spores each month; some settle beside their parents, and others drift off to find another ship.

Few intelligent creatures prey on them, since most soon learn the cost. Omnivorous void scavengers sometimes try to eat them but are usually driven off by a tentacle swipe. The purple glue that anchors the shell is prized: it resists water and fire and even has 5% magic resistance. Because live leeches are so hazardous to collect and keep, the glue is scarce and very costly.