Vapor Imp

A vapor imp needs a full turn to swap between its two shapes: a drifting red cloud with two burning eyes at its core, or a potbellied, bright red humanoid two feet tall with claws, a pointed tail, long ears, curled horns and a huge droopy nose over a tiny-toothed grin, red vapor forever seeping from its skin. In either shape it never stops screaming, groaning and cackling. Vapor imps speak telepathically among themselves but never to their prey.

On nights when violent storms churn the sea, they surge up from the seabed to waylay ships. The first warning is shrill laughter mixed into the howl of the wind; then the waves themselves seem to become grinning faces, claws and tails wrapped in spreading red fog. The imps rock and shove the hull, then over the next hour engulf it as mist, seeping through doors and portholes to reform inside, scaling masts, tearing at rigging and loosening cargo. Disabling the ship always comes before murdering the crew.

In physical form an imp has AC 4, cannot fly, and deals 1d6 with a chilling touch that allows no save. As mist it flies at AC 1, attacks against it take -2, and it cannot do anything physical, so anyone touching it suffers only 1 point of chill. It prefers solid form, which allows more mayhem.

Sailors who interfere get thrown into the hold, locked in a cabin or pitched over the side. Each imp has Strength 4, and a group can shift a character only if their combined Strength beats his, dragging him one foot per round for each point of difference.

Only magical weapons touch them. They cannot be turned and ignore sleep, charm, cold-based spells, paralysis and poison. A lightning bolt, natural or magical, has a 10% chance of making a struck imp split off a copy of itself in mist form.

They swarm most thickly in one blood-red tropical sea but also haunt other warm oceans. Schools of 10d4 share shallow seabed lairs lined with rotting weeds and debris, sleeping through the day and emerging at night to find storm-battered ships. They keep trinkets from plundered vessels as souvenirs, caring nothing for their value.

Vapor imps ignore other sea creatures unless attacked, then fight savagely. They neither eat, drink nor breathe, drawing vigor instead from the thunder and lightning of ocean storms.