Demogorgon, Prince of Demons (CR 23)

Huge Outsider (Aquatic, Chaotic, Evil, Extraplanar, and Tanar'ri)
Alignment: Chaotic evil
Initiative: +12(+8 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., true seeing, Listen +38, and Spot +38
Languages: Abyssal, Aquan, Common; telepathy 300 ft.

AC: 43 (-2 size, +8 Dex, +27 natural), touch 16, flat-footed 35
Hit Dice: 27d8+378 (499 hp); DR: 20/cold iron and good
Fort +29, Ref +23, Will +21
Speed: 30 ft. and Swim 50 ft.
Space: 15 ft.; Reach 15 ft.
Base Attack +27; Grapple +49
Attack: Melee: 2 tentacles +39 and 2 bites +35 and tail slap +35
Damage: Tentacle 1d8+14 plus rot, bite 2d6+7, tail slap 2d6+7 plus energy drain
Special Attacks/Actions: dual action, gaze, summon tanarri
Attack Options: Combat Expertise, Spring Attack, Whirlwind Attack
Abilities: Str 38, Dex 27, Con 38, Int 26, Wis 22, Cha 28
Special Qualities: SQ amphibious, tanarri traits, fast healing 10; Immunities: electricity, poison; Resist: acid 10, cold 10, fire 10; SR 34
Feats: Alertness, Combat Expertise, Combat Reflexes, Dark Speech, Dodge, Improved Initiative, Mobility, Multiattack, Spring Attack, Whirlwind Attack,
Skills: Bluff +39, Concentration +44, Diplomacy+43, Intimidate +41, Jump +52, Knowledge (arcana) +38, Knowledge (history) +38, Knowledge (nature) +38, Knowledge (the planes) +38, Listen +38, Move Silently +38, Search +38, Sense Motive +36, Spellcraft+40, Spot +38, and Swim +52
Advancement: -
Climate/Terrain:
Organization:
Treasure/Possessions: -

Source: Book of Vile Darkness
Fiendish Codex I

Gaze (Su): Each of Demogorgon's heads has its own gaze attack. Any creature within 30 feet of the demon lord must make two successful DC 32 Will saving throws each round at the beginning of its turn, the first save against Demogorgon's beguiling gaze and the second save against his insanity gaze. Creatures can avoid the need to make saving throws by averting their eyes or wearing a blindfold.

Demogorgon can actively target foes with his beguiling gaze and insanity gaze, in which case each gaze requires a standard action to activate. Thanks to his dual actions ability, Demogorgon can use both gazes in the same round. He must split these gaze attacks between two targets to gain their effects. Conversely, as a standard action, he can lock the gazes of both heads on a single target and use a special hypnosis gaze effect. Demogorgon cannot use his hypnosis gaze during the same round in which he uses his beguiling gaze, his insanity gaze, or both.

Beguiling Gaze: The gaze attack of Aameul, Demogorgon's left head, is the equivalent of a charm monster spell (DC 32) with a range of 30 feet.

Insanity Gaze: The gaze attack of Hethradiah, Demogorgon's right head, is the equivalent of an insanity spell (DC 32) with a range of 30 feet.

Hypnosis Gaze: If Demogorgon locks the gazes of both heads upon a single target within 30 feet, that creature is affected as though by a hypnotism spell. Only a target with 15 Hit Dice or more is allowed a DC 32 Will saving throw to resist the effect.

The save DCs for all three gaze attacks are Charisma-based.

Rot (Su): Any living creature touched by Demogorgon's tentacles must succeed on a DC 37 Fortitude save, or its flesh and bones begin to rot. The creature takes 1d6 points of Constitution damage immediately and 1 point of Constitution damage every hour thereafter until it dies or a remove disease spell is cast. The spell stops further damage, but lost Constitution points return only with natural healing and cannot be restored with magic. The save DC is Constitution-based.

Summon Tanar'ri (Sp): Once per day, Demogorgon can automatically summon ld8 vrocks, 1d6 hezrous, 1d4 glabrezu, 1d3 nalfeshnees, 1 marilith, or 1 balor. This ability is a equivalent of a 9th-level spell (CL 20th).

Amphibious (Ex): Even though Demogorgon has the aquatic subtype, he can survive indefinitely on land.

Spell-Like Abilities (CL 20th): At will - astral projection, contagion (DC varies), desecrate, detect good, detect law, fly, greater dispel magic, greater teleport, project image, telekinesis (DC 24), unhallow, unholy blight (DC 23) 3/day - feeblemind (DC 24), symbol of death (DC 27) 1/day - dominate person (DC 28)

Updated to Fiendish Codex I

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.

Chaotic Subtype

A subtype usually applied only to outsiders native to the chaotic-aligned Outer Planes. Most creatures that have this subtype also have chaotic alignments; however, if their alignments change they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has a chaotic alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the chaotic subtype overcomes damage reduction as if its natural weapons and any weapons it wields were chaotic-aligned (see Damage Reduction).

Evil Subtype

A subtype usually applied only to outsiders native to the evil-aligned Outer Planes. Evil outsiders are also called fiends. Most creatures that have this subtype also have evil alignments; however, if their alignments change, they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has an evil alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the evil subtype overcomes damage reduction as if its natural weapons and any weapons it wields were evil-aligned (see Damage Reduction).

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.

Tanarri Subtype

Most demons encountered outside of the Abyss are tanar'ri. The most populous of the demon subtypes, the tanar'ri form the largest and most diverse group of demons. They are the unchallenged masters of the Abyss at this time. The first tanar'ri were forged from the souls of the first humanoids drawn to the Abyss. Most tanar'ri incorporate humanoid features into their forms as a result of their close ties to the mortal realm.

Traits: A tanar'ri possesses the following traits (unless otherwise noted in a creature's entry).