Ironmaw (CR 13)

Huge Plant (Extraplanar)
Alignment: Always neutral evil
Initiative: -1 (Dex); Senses: Listen +14 and Spot +13

AC: 25 (-2 size, -1 Dex, +18 natural), touch 7, flat-footed 25
Hit Dice: 12d8+72 (126 hp); DR: 15/magic slashing
Fort +14, Ref +3, Will +5
Speed: 10 ft.
Space: 15 ft./15 ft. (60 ft. with tendril)
Base Attack +9; Grapple +27
Attack: Tendril +17 melee
Full Attack: 4 tendrils +17 melee and bite +12 melee
Damage: Tendril 2d6+10 19-20, bite 1d8+5
Special Attacks/Actions: Attach, engulf, illness, tendrils, wounding
Abilities: Str 30, Dex 9, Con 23, Int 4, Wis 13, Cha 14
Special Qualities: Acid resistance 10, cold immunity, electricity immunity, plant traits, sonic resistance 10, SR 30
Feats: Alertness; Cleave; Great Cleave; Improved Critical (tendril); Power Attack
Skills: Hide +6*, Listen +14, and Spot +13
Advancement: 13-16 HD (Huge); 17-36 HD (Gargantuan)
Climate/Terrain: Temperate and warm forest, hill, and marsh (Abyss)
Organization: Solitary, pair, or stand (3-6)
Treasure: 1/10 coins, 50% goods, 50% items

Source: Fiend Folio

An ironmaw's territory is easily spotted by a trained observer. No other wildlife goes near its "home," and the ground is often littered with the remains of the creature's past victims. But most creatures never know they're near an ironmaw until it strikes.

An ironmaw stands 20 to 30 feet high. It closely resembles an oak tree, although its green leaves are covered with tiny splotches the color of fresh blood. Its tendrils are kept wrapped around its upper trunks when not in use, and its mouth remains closed until it attacks. An ironmaw tends to stay in one place for an extended period of time. It attacks anything that comes within range of its tendrils, even if it has recently fed. Ironmaws usually relocate only when a stand grows large enough that there isn't enough food to support them all, at which point one or more of the creatures will move to greener pastures.

Ironmaws speak Abyssal.

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.