No Oni, Byoki (CR 15)

Large Outsider (Evil and Shadowlands)
Alignment: Always chaotic evil
Initiative: +3 (Dex); Senses: Listen +18 and Spot +18

AC: 16 (-1 size, +3 Dex, +4 natural), touch 12, flat-footed 13
Hit Dice: 13d8+52 (110 hp); DR: 15/jade
Fort +14, Ref +11, Will +10
Speed: 40 ft.
Space: 10 ft./10 ft.
Base Attack +13; Grapple +12
Attack: 2 claws +16 melee
Full Attack: 2 claws +16 melee
Damage: Claw 1d6+4 plus disease
Special Attacks/Actions: Disease, infection, spell-like abilities, stench, fear aura
Abilities: Str 19, Dex 17, Con 19, Int 12, Wis 14, Cha 12 (Ego: 8)
Special Qualities: oni qualities, regeneration 3
Feats: Cleave; Great Cleave; Great Fortitude; Improved Bull Rush; Power Attack
Skills: Climb +20, Concentration +20, Diplomacy +3, Intimidate +17, Jump +24, Knowledge (Shadowlands) +17, Listen +18, Sense Motive +18, Spot +18, and Survival +18
Advancement: 14-20 HD (Large); 21-30 HD (Huge); 31-39 HD (Gargantuan)
Climate/Terrain: Shadowlands
Organization: Solitary or plague (1 plus 2-8 plague zombies)
Treasure/Possessions: Standard

Source: Oriental Adventures

Disease (Ex): Zombie plague-claw, Fort save (DC 20); incubation period 1 day; damage 1d4 temporary Con and 1d4 temporary Int. A character who dies from zombie plague immediately rises as a plague zombie. (See Disease.)

Infection (Ex): In addition to transmitting zombie plague with its attacks, the byoki no oni can infect nearby characters when it is struck in combat. Whenever the oni suffers damage (higher than its damage reduction), all characters within 5 feet of the oni must succeed at Reflex saving throws (DC 10 + the damage actually dealt to the oni, after damage reduction) or risk infection. Characters who fail the Reflex save must make Fortitude saves against the disease as described above.

Spell-Like Abilities: At will - cloudkill, cloud of Tainit, contagion, deeper darkness, desecrate, stinking cloud; 3/day - Tainted aura. These abilities are as the spells cast by a 13th-level mahotsukai (save DC 18 + spell level).

Stench (Ex): Any creature within 10 feet of a byoki no oni must make a successful Fortitude save (DC 20) or become nauseated. Nauseated creatures are unable to attack, cast spells, concentrate on spells, or do anything else requiring attention. The only action such a character can take is a single move (or move-equivalent) action per turn.

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 17) or become shaken. Shaken creatures suffer a -2 morale penalty on attack rolls, weapon damage rolls, and saving throws.

Regeneration (Ex): Oni rake 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.

Plague Zombies

Plague zombies are mindless servitors of the byoki no oni that created them. They look like animated corpses covered with oozing sores and pustules, and are surrounded by a sour odor like Dancid milk. They have the characteristics of ordinary zombies of the appropriate size, except that they can transmit zombie plague with their attacks:

Disease (Ex): Zombie plague - slam, Fort save (DC 10 + 1/2 the zombie's HD); incubation period 1 day; damage 1d4 temporary Con and 1d4 temporary Int. A character who dies from zombie plague immediately rises as a plague zombie.

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.