Lusca

This behemoth has three huge, snapping sharklike heads on short, scaly necks, while its lower body appears to be that of a gigantic octopus with eight muscular tentacles.

Lusca (CR 17)

Gargantuan Magical Beast (Aquatic)
Alignment: Chaotic Evil
Initiative: +4
Senses: Darkvision 60 feet, Low-Light Vision; Perception +28
Speed: 10 feet, Swim 40 feet, jet 200 feet
Space: 20 feet

Defense

Armor Class: 32, touch 6, flat-footed 32 (+26 natural, -4 size)
Hit Points: 270 (20d10+160)
Saving Throws: Fort +20, Ref +12, Will +11
Immunity: electricity, poison

Offense

Melee: 3 bites +27 (2d8+10/19-20), 8 tentacles +21 (1d8+5 plus Grab)
Reach: 20 feet
Special Attacks: Constrict (1d8+5 plus poisonous suckers), Rend ship
Spell-Like Abilities (CL 18th; Concentration +22):

3/day- Chain Lightning (DC 20), Geyser* (DC 19)
1/day- summon (level 8, 1d3 dire sharks 50%), Vortex* (DC 21)

Statistics

Str	Dex	Con	Int	Wis	Cha
30 (+10)	11 (+0)	26 (+8)	13 (+1)	21 (+5)	18 (+4)

Base Attack Bonus: +20
CMB +34 (+38 Grapple)
CMD 44
Feats: Awesome Blow, Critical Focus, Powerful Maneuvers, Improved Critical (bite), Improved Initiative, Sickening Critical, Snatch, Vital Strike, Weapon Focus (bite)
Skills: Perception +28, Stealth +11, Swim +41
Languages: Aquan, Common
Special Qualities: tenacious grapple

Special Abilities

Poisonous Suckers (Ex)

A creature constricted by a lusca's tentacles is exposed to its deadly venom. Lusca Venom: Constrict-injury; save Fort DC 28; frequency 1/round for 6 rounds; effect 1d6 Dex; cure 2 consecutive saves.

Rend Ship (Ex)

As a full-round action, a lusca can attempt to use four of its tentacles to grapple a ship of its size or smaller by making a combat maneuver check opposed by the ship's captain's Profession (sailor) check; the lusca receives a cumulative +4 bonus on the check for each size category smaller than Gargantuan the ship is. If the lusca grapples the ship, it holds the ship motionless; it can attack targets anywhere on or within the ship with its tentacles, but can't attack foes at all with its shark heads. Each round it maintains its hold on the ship, it automatically deals bite damage to the ship's hull.

Tenacious Grapple (Ex)

A lusca does not gain the grappled condition if it grapples a foe with its tentacles.

Ecology

Environment: Warm Oceans
Organization: solitary
Treasure: double

Luscas are among the most feared predators in the open ocean, their snapping shark heads and writhing tentacles spelling the end for many crews. A lusca's presence can first be felt in the air, as its body naturally conducts electricity, and sailors who have encountered the being claim that thunderclouds seem to roll in alongside the creature.
Ravenous and unpredictable, a lusca claims wide swaths of territory in order to maximize the number of ships it can sink and crews it can feast upon. While luscas prefer to make quick meals of the sailors onboard a ship, they will eat just about any aquatic creature, and even giant octopuses and whales know to steer clear of a hungry lusca.
The average lusca is 90 feet from tentacle to snout and weighs 3,800 pounds.