Chelicera (CR 6)

Medium Vermin
Alignment: Always neutral
Initiative: +4 (Dex); Senses: darkvision 60 ft., scent, and Listen +9

AC: 19 (+4 Dex, +5 natural), touch 14, flat-footed 15
Hit Dice: 12d8+12 (66 hp)
Fort +9, Ref +8, Will +5
Speed: 30 ft., climb 30 ft.
Space: 5 ft./5 ft.
Base Attack +9; Grapple +17
Attack: Claw +13 melee
Full Attack: 2 claws +13 melee and bite +8 melee
Damage: Claw 1d6+2, Bite 1d8+1
Special Attacks/Actions: Blood drain, improved grab
Abilities: Str 14, Dex 19, Con 12, Int -, Wis 13, Cha 12
Special Qualities: immunity to sonic, mimicry, vermin traits
Feats: Weapon Finesse
Skills: Climb +10, Hide +12, and Listen +9
Advancement: 13-16 HD (Medium); 17-36 HD (Large)
Climate/Terrain: Warm mountains
Organization: Solitary or pack (2-8)
Treasure/Possessions: Standard

Source: Monster Manual III

Cheliceras always attempt to ambush their foe, leaping from the shadows when they lure a creature to their nest. As they cannot truly gauge the odds of success, they always spring to the attack even if a large group enters, subsequently fleeing if the battle turns against them.

Blood Drain (Ex): A chelicera can suck the blood from a living creature by making a successful grapple check. If it pins the foe, it drains blood, dealing 1d4 Constitution drain each round that it makes a successful grapple check.

Improved Grab (Ex): To use this ability, a chelicera must hit with a claw attack. It can then attempt to start a grapple as a free action without provoking attacks of opportunity. If it wins the grapple check, it establishes a hold and can try to pin the creature on a subsequent round.

A chelicera has a +4 racial bonus on grapple checks and uses its Dexterity modifier instead of its Strength modifier when grappling.

Mimicry (Ex): A chelicera can repeat any noise it hears as a free action. This ability works much like ghost sound (Will DC 17 disbelief), except that the sound is always centered on the chelicera itself. The creature's favorite tactic is to reproduce garbled or faint speech, causing the potential prey to move closer for a better listen. The save DC is Charisma-based.

Skills: Cheliceras have a +8 racial bonus on Hide checks and Listen checks. A chelicera also has a +8 racial bonus on Climb checks and can always choose to take 10 on a Climb check, even if rushed or threatened.