Monstrous Scorpion, Colossal (CR 12)

Colossal Vermin
Alignment: Always Neutral
Initiative: -1 (Dex); Senses: darkvision 60 ft., tremorsense 60 ft., and Spot +4

AC: 26 (-8 size, -1 Dex, +25 natural), touch 1, flat-footed 26
Hit Dice: 40d8+120 (300 hp)
Fort +25, Ref +12, Will +13
Speed: 50 ft.
Space: 40 ft./30 ft.
Base Attack +30; Grapple +58
Attack: Claw +32 melee
Full Attack: 2 claws +34 melee and sting +29 melee
Damage: Claw 2d8+12, sting 2d8+6 plus poison
Special Attacks/Actions: Improved grab, constrict 2d8+12, poison
Abilities: Str 35, Dex 8, Con 16, Int -, Wis 10, Cha 2
Special Qualities: Vermin
Feats: -
Skills: Climb +16, Hide -12, and Spot +4
Advancement: 41-60 HD (Huge)
Climate/Terrain: Warm desert
Organization: Solitary or colony (2-5)
Treasure/Possessions: None

Source: Monster Manual

Improved Grab (Ex): To use this ability, the monstrous scorpion must hit with its claw attack. If it gets a hold, it hangs on and stings.

Squeeze (Ex): A monstrous scorpion that gets a hold on an opponent of its size or smaller automatically deals damage with both claws, biting and stinging at its full attack value.

Poison (Ex): Fortitude save DC 54, initial and secondary damage 2d8 Strength.

Skills: A monstrous scorpion receives a +4 racial bonus to Climb, Ride, and Spot checks.

Monstrous scorpions are likely to attack any creature that approaches, and they usually charge prey.

Monstrous scorpions are vicious predators that make unnerving scuttling noises as they speed across dungeon floors. A monstrous scorpion has a low, flat body: 80 feet long, 40 feet wide* and 10 feet high**.
*The number includes the scorpion's body and its legs; the actual body width is about a third of the total.
**The number indicates the height of the creature's body; the creature's stinger usually is held about as high off the ground as the creature is wide.