Teratomorph (CR 16)

Gargantuan Ooze
Alignment: Always neutral
Initiative: -3 (Dex)

AC: 3 (-4 size, -3 Dex), touch 3, flat-footed 3
Hit Dice: 28d10+140 (294 hp)
Fort +14, Ref +6, Will +4
Speed: 30 ft., fly 50 ft. (poor), swim 90 ft.
Space: 20 ft./15 ft.
Base Attack +21; Grapple +29
Attack: Slam +28 melee
Full Attack: Slam +28 melee
Damage: Slam 4d6+16 plus entropic touch
Special Attacks/Actions: Entropic touch, portalwake, warp reality
Abilities: Str 32, Dex 5, Con 20, Int -, Wis 1, Cha 1
Special Qualities: detect law, dimensional instability, immunities, ooze traits, SR 32
Feats: -
Skills: -
Advancement: 29-36 HD (Gargantuan); 37-84 (Colossal)
Climate/Terrain: Any aquatic and underground
Organization: Solitary
Treasure/Possessions: Standard

Source: Monster Manual II

Entropic Touch (Su): The entropic energy that surges through a teratomorph's shapeless body causes horrible transformations in living creatures that come into contact with it. If a creature struck by a teratomorph's slam attack fails a Fortitude saving throw (DC 29) its body transforms some way, causing one of the following effects:

Portalwake (Su): The presence of a teratomorph places tremendous strain on the borders between the planes, causing tears and rips to appear nearby Each round, one creature within a 120-foot radius of the teratomorph, chosen at random, must make a Reflex saving throw (DC 19) or be moved to a random plane as though by a plane shift spell.

Warp Reality (Su): The potent chaotic energy that surges through and out of a teratomorph's body can have amazing effects on the surrounding terrain. When the monster is at rest, this energy is calm, but when the monster moves or attacks, the energy lashes out in a 120-foot emanation. These ripples of chaos cause the surrounding terrain to warp and writhe, imposing a -4 circumstance penalty on attack rolls and Dexterity checks for all creatures in the area except the teratomorph.

Every round that this reality warp persists, there is a 10% chance that the chaotic energy manifests in a more dramatic manner. Such chaos manifestations duplicate spell effects.

Roll 1d20 and refer to the appropriate line on the following table to determine the spells effects produced. These effects function as the spells of the same names (caster level 20th; save DC 10 + spell level), except that they affect all the appropriate targets (except the teratomorph) within the warped reality area and last for 1 round.

1-4Entangle and Obscuring Mist
5-8Colorspray and Glitterdust
9-12Stinking Cloud and Spike Growth
13-14Spike Stones and Cloudkill
15-16Insect Plague and Mind Fog
17-18Acid Fog and Transmute Rock to Mud
19Fire storm and reverse gravity
20Earthquake and prismatic spray
(roll once for all affected creatures)

Blindsight (Ex): A teratomorph is blind, but its entire body is a primitive sensory organ that can ascertain prey by scent and vibration. This ability enables it to discern objects and creatures within 240 feet. A teratomorph usually does not need to make Spot or Listen checks to notice creatures within range of its blindsight.

Detect Law (Su): A teratomorph has a continual detect law ability (as the spell) with a range of 20 feet.

Dimensional Instability (Su): Each time an opponent strikes a teratomorph with a weapon, there is a chance that the portion of the creature's body struck simply doesn't exist at that instant. Any melee or ranged attack directed at the teratomorph has a 20% miss chance that cannot be avoided with spells such as true seeing or true strike. Dimensional anchor negates this ability, reducing the miss chance to 0% for the duration of the effect.

Immunities (Ex): A teratomorph is immune to lightning, acid, and all spells with the chaotic descriptor.

The teratomorph is a mindless creature. When it isn't eating, it is on the move looking for something to eat. It surges forth to attack any Small or larger creature that pass within range of its blindsight, but it ignores creatures smaller than this.

A teratomorph attacks by extruding a massive wave of chaotic protoplasm to smash its prey. Not only does this attack deal extensive bludgeoning damage, also infuses the creature touched with raw chaos.