Sea Demon

Picture an octopus scaled up to rival a sailing ship. The lesser sea demon has a body 15 to 18 feet across and ten arms averaging 30 feet.

On land it crawls on half its arms and strikes with the rest; at sea two arms anchor it while the others attack. An arm's first strike deals 1d8, after which it squeezes automatically for 2d8 each round, and two rounds later the victim reaches the beak, which bites for 5d4. Each arm grips with 18/76 Strength, so anyone that strong avoids the crushing but still stays caught. Twelve points of slashing damage sever an arm, and that damage never reduces the monster's own hit points. Losing half its attacking arms makes it withdraw. Underwater it then releases a 40 x 60 x 60 foot ink cloud: those inside are blind while within and for 1d4 rounds after leaving, and their sound and pressure senses fail for 2d4 turns.

It preys on ships near its lair. Each mile of surface distance between ship and lair gives a 20% chance the vessel is ignored. The beast needs two turns to rise and 2 to 12 more to catch up, and a seized ship halts within a turn. With six arms on the hull it cuts seaworthiness by 2d4% per round (1d4 hull points under optional hull damage rules) while plucking sailors off the deck.

If it loses four or more arms, but not over half, it sinks 500 feet below the keel (or halfway to the bottom in shallows) and spins. After one turn a whirlpool forms. Only a ship already fleeing before then escapes; any other is held 1d4 turns before it may try to break out, which demands working sails or manned oars and a seaworthiness check. Failure destroys the ship. The vortex lasts at most five turns, and afterward the monster must rest a full day and will not pursue. It remembers any ship that escaped, senses it from 10 miles away (double its normal range) and attacks it on sight.

Found at sea and along coasts, it usually lairs underwater but may den ashore in humid tropical or subtropical lands. It hates all life, other sea demons most of all, so it is met alone, 80% of the time in or near its lair. Lost arms regrow 3 feet per week each, and it will not attack ships until wounded arms are at least half healed.

It eats giant sea creatures, small whales and anything else it can catch, hunting ashore when local waters are stripped. Perhaps it first mistook hulls for whales seen from below; either way, it has learned that crews are food.

The greater sea demon has twelve arms (ten used to attack) up to 40 feet long on a 20 to 25 foot body and lairs below 1,000 feet. Its arms grip at 18/91 Strength and take 20 points to cut through. The beak deals 5d6 and cracks coral or giant clam shells. It reduces seaworthiness by 4d4% per round (2d4 hull points), crushes small boats easily, regrows arms at four feet per week and spreads a 60 x 80 x 80 foot ink cloud.