Blood Elemental (CR 6)

Medium Outsider
Alignment: Always neutral evil
Initiative: +1 (Dex); Senses: Listen +8 and Spot +8
Languages: Blood Elemental

AC: 20 (+1 Dex, +9 natural), touch 11, flat-footed 19
Hit Dice: 5d8+12 (37 hp); DR: 5/magic
Fort +7, Ref +5, Will +4
Speed: 20 ft., swim 90 ft.
Space: 5 ft./5 ft.
Base Attack +5; Grapple +0
Attack: Slam +8 melee
Full Attack: Slam +8 melee
Damage: Slam 1d8+4
Special Attacks/Actions: Bloodbath, cause insanity
Abilities: Str 17, Dex 12, Con 17, Int 10, Wis 11, Cha 19
Special Qualities: incomprehensible, immunities (critical hits, mind-affecting effects, stunning), outsider traits
Feats: Cleave; Power Attack
Skills: Listen +8, Move Silently +9, Search +8, Spot +8, and Swim +19
Advancement: 6-10 HD (Large); 11-15 HD (Huge)
Climate/Terrain: Any
Organization: Solitary
Treasure: None

Source: Web

Bloodbath (Ex): With a successful grapple check (grapple bonus +12, including a +5 racial bonus on grapple checks), a blood elemental may engulf a creature of up to its own size category. An engulfed creature is subject to drowning (see the Drowning). The elemental may eject the engulfed creature at any time. A victim that is still alive when it emerges from the blood elemental's body (whether by escaping the monster's hold or by being ejected) takes 1d6 points of Wisdom damage because of the strain on its sanity that the sensation of drowning in blood produced. Furthermore, the victim creature must make a successful Fortitude save (DC 15) on emerging or be nauseated for 2d6 rounds.

Cause Insanity (Su): Once per day, a blood elemental can produce an effect identical to that of the insanity spell (caster level 13th; save DC 16).

Immunities (Ex): The blood elemental's alien psychology and physiology make it immune to critical hits, mind-affecting effects, stunning.

Incomprehensible (Ex): Because of its alien mentality, a blood elemental does not understand verbal communication of any sort, nor can its own gurgling language be understood by any creature except its own kind. A blood elemental is immune to all language-dependent spells and effects, and no mundane or magical effect that usually allows verbal communication (including a tongues spell or a monk's tongue of the sun and moon ability) functions with respect to it.

Outsider Traits: A blood elemental has darkvision (60-foot range). It cannot be raised or resurrected.