Dire Snake (CR 5)

Huge Animal
Alignment: Always neutral
Initiative: +5 (Dex); Senses: low-light vision, scent, Listen +8, and Spot +8

AC: 18 (-2 size, +5 Dex, +5 natural), touch 13, flat-footed 13
Hit Dice: 7d8+24 (55 hp)
Fort +8, Ref +10, Will +6
Speed: 30 ft., climb 20 ft., swim 20 ft.
Space: 15 ft./10 ft.
Base Attack +5; Grapple +20
Attack: Bite +10 melee
Full Attack: Bite +10 melee
Damage: Bite 2d6 +10 plus poison
Special Attacks/Actions: Constrict 1d6+10, improved grab, poison
Abilities: Str 24, Dex 20, Con 16, Int 1, Wis 13, Cha 11
Special Qualities:
Feats: Alertness; Endurance; Toughness
Skills: Balance +14, Climb +15, Hide +6, Listen +8, and Spot +8
Advancement: 8-12 HD (Huge); 13-16 HD (Gargantuan)
Climate/Terrain: Temperate and warm land, aquatic, and underground
Organization: Solitary
Treasure/Possessions: None

Source: Monster Manual II

Constrict (Ex): With a successful grapple check, a dire snake can constrict a grabbed opponent, dealing 1d8+10 points of bludgeoning damage.

Poison (Ex): A dire snake delivers its poison (Fortitude save DC 16) with each successful bite attack. The initial and secondary damage is the same (1d6 points of Constitution damage).

Improved Grab (Ex): If a dire snake hits an opponent that is at least one size category smaller than itself with bite attack, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +20). If it gets a hold, it can also constrict in the same round. Thereafter, the dire snake has the option to conduct the grapple normally, or simply use its jaws to hold the opponent (-20 penalty on grapple check, but the dire snake is not considered grappled). In either case, each successful grapple check it makes during successive rounds automatically deals bite and constrict damage.

Scent (Ex): A dire snake can detect approaching enemies, sniff out hidden foes, and track by sense of smell.

Skills: A dire snake receives a +4 racial bonus on Hide, Listen, and Spot checks, and a +8 racial bonus on Balance checks.

Saving Throws: A dire animal has all good saves.

Dire animals are fierce fighters that prefer melee combat. They are territorial, attacking anything that enters their territory or threatens their lairs.