Battlebriar (CR 15)

Huge Plant
Alignment: Usually neutral
Initiative: -2 (Dex); Senses: darkvision 60 ft. and low-light vision

AC: 30 (-2 size, -2 Dex, +24 natural), touch 6, flat-footed 30
Hit Dice: 25d8+200 (312 hp)
Fort +22, Ref +6, Will +10
Speed: 30 ft.
Space: 15 ft./10 ft.
Base Attack +18; Grapple +37
Attack: Slam +28 melee
Full Attack: 4 slams +28 melee
Damage: Slam 2d6+11/19-20
Special Attacks/Actions: Impale, improved grab, thorn volley, trample 2d6+16
Abilities: Str 32, Dex 6, Con 27, Int 5, Wis 10, Cha 7
Special Qualities: plant traits, resistance to electricity 20 and fire 20, thorn field
Feats: Awesome Blow; Cleave; Great Cleave; Improved Bull Rush; Improved Critical (slam); Improved Natural Attack (slam); Iron Will; Power Attack; Weapon Focus (slam)
Skills: Hide +18*
Advancement: 26-50 HD (Huge)
Climate/Terrain: Temperate forests
Organization: Solitary
Treasure: None

Source: Monster Manual III

This six-legged lionlike creature has a body made of writhing vines and thorns. Each of its gorillalike pairs of limbs is slightly shorter than the pair in front of it - its forelimbs are the longest, the middle pair of limbs slightly shorter, and its rear pair of legs the shortest of all. Long thorns protrude from every part of the creature's body, making it seem impossible to approach or move around the creature without risking serious injury.

Plants magically engineered to serve as massive living siege engines, battlebriars on a field of battle can easily destroy massed formations of lesser troops. Although created for war, battlebriars have long since escaped the control of their creators, and they now roam through forest and field alike. A single battlebriar is capable of destroying a small town, and for this reason it is an event of major importance when one is seen near a settlement of any size.

Battlebriars possess a rudimentary intelligence but no capacity for speech. On the few times that druids and spellcasters of similar skill have been able to communicate with them, battlebriars have proven intractable and uncaring. A few powerful evil druids have been able to find magical means of controlling battlebriars, and these controlled beasts make fearsome guardians.

A battlebriar walks about on all six of its limbs, but when fighting, it stands on only one set of legs, swinging both pairs of its huge forelimbs wildly. A battlebriar is almost as broad as it is tall, and compared to a humanoid of similar size, is quite squat and stocky.

Battlebriars have a tough, rubbery hide the color of drying mud, although some of the vinelike strands that run through its body are greenish in color. A massive plant, one can grow up to 15 feet in length and weigh as much as 18,000 pounds.

Battlebriars do not speak, but they understand simple words and phrases in Sylvan.