Bloodworm (CR 5)

Huge Vermin
Alignment: Always neutral
Initiative: -1 (Dex)

AC: 16 (-2 size, -1 Dex, +9 natural), touch 7, flat-footed 16
Hit Dice: 6d8 (27 hp)
Fort +5, Ref +1, Will +0
Speed: 1 ft., swim 15 ft.
Space: 10 ft./5 ft.
Base Attack +4; Grapple +7
Attack: Bite +2 melee
Full Attack: Bite +2 melee
Damage: Bite 1d8+3
Special Attacks/Actions: Improved grab, blood drain
Abilities: Str 15, Dex 8, Con 10, Int -, Wis 6, Cha 6
Special Qualities: Exposure, Vermin
Feats: -
Skills: Hide +4 and Move Silently +4
Advancement: 7-8 HD (Huge), 9-10 HD (Gargantuan)
Climate/Terrain: River of Blood (Avernus/Baator)
Organization: Solitary, Pack (3-5), Swarm (6-8)
Treasure/Possessions: None

Source: Converted

Improved grab (Ex): With a successful bite attack, a bloodworm may attempt a grapple check (+14) to pull an opponent under the surface of the river and keep her there.

Blood drain (Ex): A successful bite means the bloodworm latches on and causes 1 temporary Constitution damage every round until killed or until 12 points are drained.

Exposure: A bloodworm suffers 1 damage per round spent out of the River of Blood.

A bloodworm attacks by biting its victim, latching on and draining blood until sated or killed. It instinctively tries to pull its prey beneath the surface of the river, wrapping its long, slimy body about the victim to keep her from surfacing.

Source: "To Baator and Back" from Well of Worlds Converted by Kajal, the Southern Oracle