Encounters: Dales, Cormyr, Sembia - Forest

Treant (CR 8)

Huge Plant
Alignment: Usually neutral good
Initiative: -1 (Dex); Senses: low-light vision, Listen +8, and Spot +8
Languages: Treant, Common, Sylvan

AC: 20 (-2 size, -1 Dex, +13 natural), touch 7, flat-footed 20
Hit Dice: 7d8+35 (66 hp); DR: DR 10/slashing
Fort +10, Ref +1, Will +6

Speed: 30 ft.
Space: 15 ft./15 ft.
Base Attack +5; Grapple +22
Attack: Slam +12 melee
Full Attack: 2 slams +12 melee
Damage: Slam 2d6+9
Special Attacks: Animate trees, trample 2d6+13, double damage against objects

Abilities: Str 29, Dex 8, Con 21, Int 12, Wis 15, Cha 12
Special Qualities: Plant, fire vulnerability
Feats: Improved Sunder; Iron Will; Power Attack
Skills: Diplomacy +3, Hide -9*, Intimidate +6, Knowledge (nature) +6, Listen +8, Sense Motive +8, Spot +8, and Survival +8 (+10 aboveground)
Advancement: 8-16 HD (Huge); 17-21 HD (Gargantuan)

Climate/Terrain: Temperate forest
Organization: Solitary or grove (4-7)
Treasure: Standard

Source: Monster Manual

Treants prefer to watch potential foes carefully before attacking. They often charge suddenly from cover to trample the despoilers of forests. If sorely pressed, they animate trees as reinforcements.

Animate Trees (Sp): A treant can animate trees within 180 feet at will, controlling up to two trees at a time. It takes a full round for a normal tree to uproot itself. Thereafter it moves at a speed of 10 and fights as a treant in all respects. Animated trees lose their ability to move if the treant who animated them is incapacitated or moves out of range. The ability is otherwise similar to liveoak as cast by a 12th-level druid.

Trample (Ex): A treant or animated tree can trample Medium-size or smaller creatures for 2d12+5 points of damage. Opponents who do not make attacks of opportunity against the treant or animated tree can attempt a Reflex save (DC 20) to halve the damage.

Double Damage against Objects (Ex): A treant or animated tree that makes a full attack against an object or structure deals double damage.

Fire Vulnerability (Ex): A treant or animated tree takes double damage from fire attacks unless the attack allows a save, in which case it takes double damage on a failure and no damage on a success.

Half Damage from Piercing (Ex): Piercing weapons deal only half damage to treants, with a minimum of 1 point of damage.

Skills: Treants receive skills as though they were fey. They have a +16 racial bonus to Hide checks made in forested areas.

Faerûnian Random Encounters by Region and Locale