This NPC was donated by M Jason Parent. It uses the core rules (for the Giant Octopus) plus the Ooze Creature template from Green Ronin's Advanced Bestiary. If you do not have a copy of the Advanced Bestiary, just ignore the Create Spawn ability of this creature.

Giant Ooze Octopus
Large Ooze (augmented animal (Aquatic))
Hit Dice: 8d10+27 (71 hp)
Initiative: -1
Speed: 10 ft. (2 squares), swim 15 ft.
Armor Class: 8 (–1 size, -1 Dex), touch 8, flat-footed 8
Base Attack/Grapple: +6/+17
Attack: Tentacle +12 melee (1d4+7)
Full Attack: 8 tentacles +12 melee (1d4+7) and bite +7 melee (1d8+3)
Space/Reach: 10 ft./10 ft. (20 ft. with tentacle)
Special Attacks: Acid, bilious globule, exude ooze, improved grab, constrict
Special Qualities: Immunities, ink cloud, jet, low-light vision, mutable form
Saves: Fort +9, Ref +5, Will +1
Abilities: Str 24, Dex 9, Con 17, Int 1, Wis 8, Cha 1
Skills: Escape Artist +29, Hide +9, Listen +2, Spot +4, Swim +15
Feats: Alertness, Skill Focus (Hide), Toughness

Environment: Underground or underwater
Organization: Solitary, pair or gang (3-4)
Challenge Rating: 9
Advancement: 9–12 HD (Large); 13–24 HD (Huge)
Level Adjustment: —

These strange amorphous creatures are aggressive and hunters and scavengers, with arms reaching 10 feet or more in length. They are usually a deep purple to light grey in colour. Unlike normal octopi, these creatures seem nearly as comfortable on land as in water.

An opponent can attack a giant ooze octopus’s tentacles with a sunder attempt as if they were weapons. A giant ooze octopus’s tentacles have 10 hit points each. If a giant ooze octopus is currently grappling a target with the tentacle that is being attacked, it usually uses another limb to make its attack of opportunity against the opponent making the sunder attempt. Severing one of a giant ooze octopus’s tentacles deals 5 points of damage to the creature. A giant ooze octopus usually withdraws from combat if it loses four or more tentacles. The creature regrows severed limbs in 1d10 days.

Acid (Ex): A giant ooze octopus deals 1d6 acid damage with each natural attack. Any creature grappling with a giant ooze octopus automatically takes this acid damage each round that the grapple is maintained, in addition to any damage the giant ooze octopus might deal with a successful grapple check.

Bilious Globule (Ex): A giant ooze octopus can launch a glob of acid at foes as a ranged touch attack. This is treated as a thrown weapon with a range increment of 20 feet. The globule deals 1d6 acid damage.

Constrict (Ex): A giant ooze octopus deals 2d8+10 points of damage with a successful grapple check.

Create Spawn (Ex): Any living creature reduced to 0 or fewer hit points and lying prone in an ooze creature's exuded ooze and who fails a stabilization check transofrms into ooze, gaining the ooze template instead of losing a hit point. The new ooze creature arises on the following round with average hit points. The new ooze creature is controlled by the one that exuded the ooze that transformed it.

Exude Ooze (Su): As a full-round action, a giant ooze octopus can exude a circle of slippery ooze in a 15-foot diameter spread centered on its body. This exuded ooze remains for 2 minutes. Any non-ooze creature attempting to move in, through, or out of the area must succeed on a DC 15 Balance check or fall prone. Each round a creature remains in contact with the ooze puddle, it takes 1d6 points of acid damage. A creature prone within the acid puddle instead takes 3d6 acid damage per turn.

Immunities (Ex): Immune to mind-inflencing effects and acid.

Improved Grab (Ex): To use this ability, a giant ooze octopus must hit an opponent of any size with any natural weapon attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold. If the attack that started the grab was a tentacle attack, it can also immediately constrict.

Ink Cloud (Ex): If underwater, a giant ooze octopus can emit a cloud of jet-black ink 20 feet high by 20 feet wide by 20 feet long once per minute as a free action. The cloud provides total concealment, which the octopus normally uses to escape a losing fight. All vision within the cloud is obscured.

Jet (Ex): While underwater, a giant ooze octopus can jet backward once per round as a full-round action, at a speed of 200 feet. It must move in a straight line, but does not provoke attacks of opportunity while jetting.

Mutable Form (Ex): A giant ooze octopus' body is only semi-solid. This allows it to squeeze through apertures and into spaces that its size would normally prevent. It is treated as two size categories smaller than it is when determining if it can fit through an opening or aperture.

Skills: A giant ooze octopus can change colors, giving it a +4 racial bonus on Hide checks.

A giant ooze octopus also can squeeze and contort its body, giving it a +30 racial bonus on Escape Artist checks.

A giant ooze octopus has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.