Legendary Snake (CR 8)

Large Animal
Alignment: Always neutral
Initiative: +7 (Dex); Senses: low-light vision, scent, Listen +15, and Spot +15 Swim +8

AC: 22 (-1 size, +7 Dex, +6 natural), touch 16, flat-footed 15
Hit Dice: 16d8+121 (193 hp)
Fort +17, Ref +17, Will +12
Speed: 30 ft., climb 30 ft., swim 30 ft.
Space: 10 ft./10 ft.
Base Attack +12; Grapple +24
Attack: Bite +19 melee
Full Attack: Bite +19 melee
Damage: Bite 1d8+12 plus poison
Special Attacks/Actions: Constrict 1d8+12, improved grab, poison
Abilities: Str 27, Dex 24, Con 24, Int 1, Wis 14, Cha 7
Special Qualities:
Feats: Alertness; Athletic; Endurance; Toughness x3
Skills: Balance +27, Climb +24, Hide +14, Listen +15, and Spot +15 Swim +8
Advancement: 17-32 HD (Large)
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 legendary snake can constrict a grabbed opponent, dealing 1d8+12 points of bludgeoning damage.

Improved Grab (Ex): If a legendary snake hits a Large or smaller opponent with a bite attack, it deals normal damage and attempts to start a grapple as a free action without provoking an attack of opportunity (grapple bonus +24). if it gets a hold, it can constrict in the same round. Thereafter, the legendary snake has the option to conduct the grapple normally, or simply use its coils to hold the opponent (-20 penalty on grapple check, but the legendary snake is not considered grappled). In either case, each successful grapple check it makes during successive rounds automatically deals bite and constrict damage.

Poison (Ex): A legendary snake delivers its poison (Fortitude save DC 25) with each successful bite attack. The initial and secondary damage is the same (1d8 points of Constitution damage).

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

Skills: A legendary snake receives a +8 racial bonus on Hide, Listen, and Spot checks, and a +16 racial bonus on Balance checks. It can use its Strength or Dexterity modifier (whichever is better) for Climb checks.

Saving Throws: A legendary animal has all good saves.