Jaculi (CR 3)

Medium Magical Beast
Alignment: Always chaotic evil
Initiative: +3 (Dex); Senses: darkvision 60 ft., low-light vision, scent, Listen +10, and Spot +10

AC: 16 (+3 Dex, +3 natural), touch 13, flat-footed 16
Hit Dice: 6d10+15 (48 hp)
Fort +7, Ref +8, Will +3
Speed: 30 ft., climb 20 ft., swim 20 ft.
Space: 5 ft./5 ft.
Base Attack +6; Grapple +9
Attack: Bite +9 melee
Full Attack: Bite +9 melee
Damage: Bite 1d6+4
Special Attacks/Actions: Animal trance, constrict 1d8+4, flying gore, improved grab
Abilities: Str 17, Dex 17, Con 15, Int 11, Wis 12, Cha 2
Special Qualities: Chameleon power, spring
Feats: Alertness; Power Attack; Toughness
Skills: Balance +11, Climb +11, Hide +10, Jump +20, Listen +10, Spot +10, and Swim +11
Advancement: 7-12 HD (Large)
Climate/Terrain: Warm forests
Organization: Solitary or coil (4-40)
Treasure/Possessions: None

Source: Serpent Kingdoms

Animal Trance (Sp): Once per day, a jaculi can sway in place and flash its eyes to hold its prey motionless. This psionic ability works like the spell of the same name (caster level 12th; save DC 9).

Constrict (Ex): On a successful grapple check, a jaculi deals 1d8+4 points of damage.

Flying Gore (Ex): A jaculi can hurl itself down on an opponent like an arrow from a point 30 feet or more above. This flying gore attack (+10 melee) deals 1d8+6 points of piercing damage from the jaculi's horns and does not provoke attacks of opportunity.

Improved Grab (Ex): To use this ability, a jaculi must hit with its bite attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can constrict. If it takes 10 or more points of damage, it flees to seek easier prey.

Chameleon Power (Sp): At will, a jaculi can psionically change the coloration of its body as a standard action to match its surroundings, gaining a +10 circumstance bonus on Hide checks.

Spring (Ex): A jaculi can gather its coils and then launch itself in a jump. The Jump DCs for both long jumps and high jumps are halved, and no running start is required. Furthermore, when jumping down, the jaculi takes damage as if it had dropped 70 fewer feet than it actually did.

Skills: A jaculi has a +4 racial bonus on Hide, Listen, and Spot checks and a +8 racial bonus on Balance, Climb, and Jump checks.

A jaculi can always choose to take 10 on a Climb check, even if rushed or threatened. A jaculi uses either its Strength modifier or its Dexterity modifier for Climb checks, whichever is higher. A jaculi has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

Jaculis are intelligent hunters that never forget past experiences. They are wise enough to attack isolated creatures, avoid falling onto pointed objects or obvious weapons, and seek out sleeping prey. A jaculi typically uses its animal trance ability to lure small birds or furred forest creatures into a nest or den, then slithers inside and uses its body to block the exit.

Against formidable foes, a jaculi begins combat by launching itself from a high spot (a tree branch or even the roof of a building) for a flying gore attack. Should it face attacks from more than a single foe - or a hard fight from its chosen victim - it springs to the nearest tree and climbs out of reach. If pursued, it jumps from tree to tree to get away, seeking a place to hide, then turns and follows its foes unseen, attacking again when conditions are advantageous.

Jaculis usually swallow small prey whole, but they can also bite and chew, savaging prey too large to swallow. Unless they are starving, they eat only prey they have killed themselves less than two days ago. When feeding hungry young, a jaculi sometimes slays a large beast and hides in or under the corpse to await vultures and other carrion-feeders, which it slays as well.