No Oni, Gekido (CR 15)

Large Outsider (Evil and Shadowlands)
Alignment: Always chaotic evil
Initiative: +3 (Dex); Senses: Listen +15 and Spot +15
Languages: Telepathy 100 ft.

AC: 15 (-1 size, +3 Dex, +3 natural), touch 12, flat-footed 12
Hit Dice: 11d8+44 (93 hp); DR: 15/jade
Fort +11, Ref +10, Will +8
Speed: 40 ft.
Space: 10 ft./10 ft.
Base Attack +11; Grapple +11
Attack: 2 claws +15 melee
Full Attack: 2 claws +15 melee
Damage: Claw 1d6+5
Special Attacks/Actions: Rage, spell-like abilities, fear aura
Abilities: Str 20, Dex 16, Con 18, Int 11, Wis 13, Cha 13 (Ego: 8)
Special Qualities: oni qualities, regeneration 3
Feats: Cleave; Improved Bull Rush; Multiattack; Power Attack
Skills: Climb +19, Hide +17, Intimidate +15, Jump +23, Knowledge (Shadow lands) +14, Listen +15, Move Silently +17, and Spot +15
Advancement: 12-15 HD (Large); 16-24 HD (Huge); 25-33 HD (Gargantuan)
Climate/Terrain: Shadowlands
Organization: Solitary, knot (2-5) , or tangle (6-36)
Treasure/Possessions: Standard

Source: Oriental Adventures

Rage (Ex): A gekido no oni's most fearsome ability is its rage, which strikes randomly when the creature is in combat. When the oni rolls a natural 19 or 20 on an attack roll, it begins to rage starting with its next turn. The oni's rage is a blinding fury that increases its Strength and Constitution scores by +6, gives it a +3 morale bonus on Will saves, and increases the save DC of its fear aura by +3 (and forces opponents who have already successfully saved to roll new saving throws). The rage also imposes a -2 penalty to its AC, but the creature's hide actually thickens, increasing its natural armor bonus from +3 to +8, for a net Armor Class gain of +3. While raging, the oni adds kick and bite attacks to its claw attacks, using the attack bonuses and damage shown below. The oni can rage three times per day, and each rage lasts 10 rounds (3 rounds plus its modified Constitution modifier of +7). With the exception of the increase to the oni's fear save DC and natural armor, this ability is otherwise identical to a barbarian's greater rage.

When raging, the gekido no oni is +30 hp; AC 18; SV Fort +14, Will +14; Ark +17/+17/+15/+15/+15 melee (1d6+8, claws [x2]; 1d6+4, kicks (X2]; 1d8+4, bite); Str 26, Con 24.

Spell-Like Abilities: At will - cloud of Taint, darkness, desecrate, doom, enlarge. These abilities are as the spells cast by an 11th-level maho-tsukai (save DC 18 + spell level). The oni cannot use its spell-like abilities when it is raging.

Fear Aura (Su): Oni are shrouded in a constant aura of terror and evil. Creatures within a 30-foot radius must succeed at a Will save (DC 16) or become shaken. Shaken creatures suffer a -2 morale penalty on attack rolls, weapon damage rolls, and saving throws.

Regeneration (Ex): Oni take normal damage from jade or Kuni crystal weapons, and from honorable or blessed weapons of at least +2 enhancement.

Immunities (Ex): Oni are immune to poison.

Resistances (Ex): Oni have cold, fire, and acid resistance 10.

Alternate Form (Su): Oni can assume any humanoid form of Small to Large size as a standard action. When using this ability, oni gain a +10 circumstance bonus on Disguise checks.

Telepathy (Su): Oni can communicate telepathically with any creature within 100 feet that has a language.

Skills: All oni receive a +10 circumstance bonus on Disguise checks when using their alternate form ability.

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).

Shadowlands Subtype

Shadowlands are the source of evil in the campaign setting of Rokugan, the festering pit from which oni crawl, slither, and fly to wreck their foul destruction on humanity. The denizens of the Shadowlands are inhuman monstrosities. Many of them are spirits bound into corporeal form, and most are shapeshifters. Of all the creatures found in the Shadowlands, only the nezumi remain uncorrupted by the foul taint of the place - all others are utterly, irredeemably evil.

Shadowlands creatures share a certain immunities and vulnerabilities. They are immune to harmful effects of the Shadowlands Taint, for they are already fully corrupted by their very nature. Even if they have damage reduction, they are harmed by jade and obsidian weapons, and they cannot regenerate or naturally heal wounds dealt by such weapons. They are also affected by crystal weapons (Chapter 8, Oriental Adventures) (Note: Non-magical weapons made out of crystal, or crystal weapons created by means other than the Craft Crystal Weapon feat, have no special properties against Shadowlands creatures.)

For purposes of detect Taint, spellcasting, and other effects, a Shadowlands creature is considered to have a Taint score equal to half its Charisma score (round down). Undead creatures add +1 to this number, while outsiders add +2.