Sluk

Sluk is an unthinking parasite that feeds on magical energy, the void's answer to the ship-trapping sargasso weed of planetary oceans. Dark blue fronds dotted with small silver nodules drift in stringy clumps called beds, each about 50 feet long, waiting for something to blunder in. Against the dark void it is almost perfectly camouflaged, and lookouts have only a 5% chance to spot it, but it stands out plainly in the flame-sea. Like a sunflower tracking the sun, it slowly turns toward sources of magic.

The weed coils around any wizard or priest, or anyone bearing at least three magic items, who blunders into a bed. On a successful hit it squeezes with Strength 18 while siphoning magic, causing 1d6 damage per round.

A bed covers 2d10 x 50 square feet, and every 50 square feet can halt five tons of ship. A vessel hitting a big enough bed at full starhelm speed drops instantly to tactical speed, and everyone aboard must pass a Dexterity check or fall. At tactical speed, the ship bleeds off a portion of its starting speed and maneuverability every round until it comes to rest. Freeing a stopped ship means hacking away the strands, which takes 1d6+3 rounds.

Magic does not affect sluk, except for cold spells, which make it shrivel and flake away at once. Any other spell simply feeds it, and if 10 spell levels in total are cast at it, it reproduces.

Sluk breeds by clinging to a trapped wooden hull and bleeding off its magic. Metal hulls resist the drain, though they still get stuck, and only a motionless ship can be bled. The number of rounds it must hold the ship still is 10 minus the ship's SR, with a minimum of 1, so an SR 4 vessel lets it reproduce in six rounds. Reproduction doubles the patch, possibly entangling the ship further; at the DM's option, cutting free takes another 1d6 rounds.

While trapped, a ship's SR drops by 1 each round, to a minimum of 1, though the reproduction count always uses the original rating. At SR 1 the ship no longer feeds the weed enough to breed. An escaped ship recovers 1 SR per hour, and the DM may rule that a helm stuck for months loses its power for good. Every round, charged items are drained of a charge. A full hour in the weed strips permanent items of magic, though removing them sooner lets them recover in 1d10 turns. Relics and artifacts are unaffected.

Space moths and skullbirds sometimes nibble on sluk, but never enough to matter.