Libertad
Legend

All oni lived two lives. Their prior life was as a kami, a spiritual being who refused or was unable to perform their divine mandate in defending someone or something. They were thus cut off from being able to influence the mortal world. In their desperation, many disgraced kami entered into deals with evil entities to gain a new mortal form on the Material Plane known as an oni. While many oni are evil or eventually become evil as a result of this deal, there are also oni who renege on their end of the bargain with the wicked patrons who gave them their new lives. There is great risk for such deniers, who face an unknown fate upon true death and will be hunted by agents of the spurned patron. But what all oni share in common is a second chance, for good or ill. The oni who turn on their patron are known as maverick oni, and are presumed to be the default PC type.
Oni vary widely in physical traits, with their subspecies sharing common features with particular giant or humanoid subspecies, but oftentimes with traits unusual to that species such as horns, a third eye, and skin tones not naturally found among said species. While an oni's creation is an individual supernatural occurrence, the event is more common than people realize. Oni of similar ideologies and circumstances often band together for safety in numbers, but oni mavericks are more likely to be different, both ideologically and physically, than their brethren who choose to serve their evil patrons. Maverick oni are instead divided into five factions, sometimes called habatsu. The three that have D&D backgrounds are Atoners (question the unjustness of their divine punishment and seek to do acts in line with preventing similar tragedies that destroyed their ward), Codifiers (create or adopt a new moral code to replace that of the gods that spurned them), and Hedonists (seek to find personal happiness for themselves are lifestimes' worth of servitude and hardship). The backgroundless factions are Free Spirits (seek to live on their own terms without any patron deity or punishment and prize personal freedom) and Saviors (the unjustness of their punishment encourages them to fight for the rights of others oppressed by systemic injustice).
Thoughts: While quite a bit of Battlezoo content pulls from Pathfinder canon more than D&D canon, the oni is perhaps the most blatantly Pathfinder lorewise. I like this one more, as it has both a compelling backstory and adventure hook and expands the variety of types beyond just the iconic "ogre mage" who is still a playable option in this book. I also like how each of the factions reflect different ways that oni deal with their past trauma. I was honestly a bit surprised to not see saviors be given a background, as they're bonafide stereotypical Good Guy material.

The base oni ancestry gets an ability score boost to either Strength or Charisma and one other score of their choice, are Medium or Large size depending on their subspecies, have an average walking speed, low-light vision or darkvision depending upon system, have the fiend, oni, and humanoid types in Pathfinder and their type is either Giant or Humanoid in D&D, and they can magically change shape between their true form and that of a specific alternate form that is a certain kind of giant or humanoid depending upon their subspecies.
Oni have the largest variety of subspecies/heritages in this book, counting nine in total. They are earth yai (Large stone giants, ignore difficult terrain from rubble and rocks), fire yai (Large fire giants, resistance to fire damage and environmental heat), ice yai (Large frost giants, resistance to cold damage and environmental cold), ja noi (Medium hobgoblins, can reroll a failed Wisdom/Will saving throw once per long rest/day), kuwa (Medium human, proficiency in Diplomacy/Persuasion, can more easily gather information and rumors), nogitsune (Medium kitsune, can change shape into a kistune anthro fox form as well as a humanoid species prevalent in the area they grew up, in Pathfinder are trained in Deception and gain the Charming Liar skill feat), onidoshi (Large ogres, proficient in Intimidation, gain Quick Coercion skill feat in Pathfinder and advantage on saves vs becoming frightened in D&D), water yai (Large storm giants, are amphibious, in Pathfinder they can create a simple garment for themselves out of water), and wind yai (Large cloud giants, are immune to all fall damage).
Thoughts: Oni tend to gravitate either towards physically-inclined or social builds, and just about every subspecies has a worthwhile effect. The D&D nogitsune gets the short end of the stick in basically getting one bonus specific shapechanging form vs more substantial benefits. The earth yai and water yai's terrain-based abilities are also quite situational based on environment. The ja noi's ability to reroll a failed Wisdom/Will save can be useful over the course of a campaign, while the fire yai and ice yai gain resistance against common damage types. The onidoshi is also quite decent, being good for Intimidation builds in both systems and likelier to resist the frightened condition in D&D.

Oni get 32 feats in D&D and 39 in Pathfinder. The first level feats are overall minor abilities, such as Gourmet (proficient in Crafting or Perception skill depending on system, also trained in cooking tools/lore), Oni Magic (learns 1 or 2 cantrips from the druid/primal list depending on system), Spirit Oni Familiar (gain a familiar who is a friend or family member who also faced a similar punishment from the divine but was saved by you), Third Eye (requires belonging to one of the yai subspecies, can shoot a ranged unarmed attack from a third eye on their forehead dealing an appropriate energy damage type), and Water Garment (water yai only, can create clothing out of water to guard themselves from harm; adds half proficiency bonus to AC in D&D when not wearing armor, is treated as medium armor in Pathfinder). Pathfinder has exclusive feats: Darksight grants darkvision, and Oni Weapon Familiarity grants training and the critical specialization effects for oni weapons and similarly themed weapons such as greatclubs and mauls.
The 4th/5th level feats common to both systems are Indomitable Maverick (can make a Will/Wisdom save once per turn when they are mentally controlled to be paralyzed instead of being forced to do something against their will), Oni's Orders (can order a target to follow one of your commands on a failed save once per hour/short rest), and Water Yai Swimmer (water yai only, increased swim speed). The Pathfinder version has a lot more feats, such as Flavor Food (can temporarily improve the taste of nonmagical food and water for up to 1 hour, has no game mechanic effects), Frozen Strike (ice yai only, once per hour can apply the slow condition on a critical hit with a melee attack), Smoke Vision (fire yai only, can see normally in smoke), and Sound Control (wind yai only, gain resistance and bonus on saves vs sonic damage and auditory effects).
The 8th/9th level feats are more overtly combat-related, such as Cloak of Winds (wind yai only, can spend reaction to gain a bonus to AC/impose disadvantage on a ranged attack depending on system and can apply to siege weapons in Pathfinder), Despairing Terror (cast Fear or impose the Frightened condition as an AoE attack depending on system), Enveloping Garment (water yai, can incorporate their water-made garments into an unarmed strike with the finesse property dealing lightning damage and can grapple targets, doesn't require a free hand in Pathfinder), Infused Criticals (deal persistent damage against a target they crit, damage type depends on subspecies), Misty Stride (can use mists to better Hide from people), Oni's Levitation (gain a fly speed for 10 minutes), Regenerative Recovery (automatically heal hit points when resting for 10 minutes in Pathfinder, rolls each Hit Die twice and uses better result on short rests in D&D), and Spiky Skin (earth yai only, can grow spikes as a reaction to being attacked in melee and deal piercing damage). The Pathfinder book has Deep Sight as an exclusive feat, granting deeper darkvision for 1 minute once per hour.
The 12th/13th level feats generally grant effects reflective of intense willpower and just regular overt power. They include Perfect Discipline (ja noi only, can reroll failed Wisdom/Will once per hour/short rest), Roaring Gale (wind yai only, can generate a gust of wind as an AoE that deals damage and forced movement), and Yai's Reach (increased reach while Large size, must have that as a natural size as a prerequisite in Pathfinder). The Pathfinder-exclusive feat is Never Again (once per hour as a reaction can suppress one effect that imposes the controlled, paralyzed, or similar condition where they're unable to act for 1 turn).
The 16th/17th level feats represent oni who master effects of great social influence and physical might. They include Contagious Whisper* (nogitsune only, can magically influence a creature once per long rest/day to do a statement if they fail a Wisdom/Will save), Oni's Regeneration (once per long rest/day can rapidly regenerate hit points and regrow lost limbs and organs for 1 minute), Repel Magic (bonus/advantage on saves vs spells and other magical effects), Voice of Earthern Power (earth yai only, can speak to earth and stone), and Yai's Growth (water and wind yai only, can become Huge and gain increased damage on weapon attacks for 1 minute, can be done once per 10 minutes in Pathfinder and once per short rest in D&D).
*This is listed as being a 12th level feat in D&D despite being grouped in with the 16th level feats, so I presume this is a typo.
Some feats have varying levels in terms of prerequisites. Hobgoblin Commander and Human Infiltrator are 1st level in D&D and 5th level in Pathfinder. In D&D, divination spells show them as members of the aforementioned humanoid species instead of an oni, and they are treated as said species for various effects and prerequisites. In Pathfinder, they gain the Adopted Ancestry feat for the relevant species and a 1st level ancestry feat of that species. Insubstantial Form is 8th level in D&D and 13th in Pathfinder; in the former system, it's a once per long rest casting of Gaseous Form, while in the latter system the oni can take on a gaseous form or also liquid if a water yai. In this case, it lasts up to 5 minutes and can be done once per hour. Vanishing Trick is 9th level in Pathfinder and 12th level in D&D, letting the oni become invisible for 10 minutes in Pathfinder once per hour, or able to cast Greater Invisibility once per long rest in D&D. Constant Levitation is 13th level in Pathfinder and 16th in D&D, granting permanent flying speed. Dredge Out Darkness is a 13th level feat in Pathfinder, where they can cast Darkness at 4th level once per hour, while in D&D it's 4th level and can cast Darkness once per long rest.
Last but not least, the Pathfinder version of oni get a new weapon type at the very end: the tetsubo. It's a 0 level item of Uncommon rarity and is an advanced melee weapon in the club group. It is two-handed and deals 1d10 damage, has the backswing, razing, and sweep traits, and the backswing and sweep traits add a +2 circumstance bonus to attack rolls made with said traits.
Thoughts: As is the case with a lot of ancestries in this book, the low-level ones are quite weak and situational. Gourmet is not going to be useful in most campaigns, while Flavor Food quite honestly doesn't deserve to be a feat at all. Oni Magic and Spirit Oni Familiar are competing against Magic Initiate in Pathfinder, and while the Third Eye sounds cool it is outdamaged by equivalent cantrips like Fire Bolt and Ray of Frost for D&D.* Of the better feats, Indomitable Maverick can be worthwhile in campaigns with enemies that deploy mind-affecting effects. For the middle-level and higher feats, Enveloping Garment can be useful for monk types in being a finesse unarmed strike that deals additional damage while grappling, and Spiky Skin is similar in granting a decently-damaging reaction-based close-range counterattack. Regenerative Recovery is pretty good at healing faster during brief periods of rest, and Oni's Levitation is a good stepping stone to Constant Levitation while still granting a decent duration of flight. Most of the 16th/17th level feats have some worthwhile choices, although Contagious Whisper and Voice of Earthen Power are rather weak at this tier of play in mimicking lower-level spells.
*Although the Yai Adept covered below rectifies this.

The final piece of content for this chapter is the Yai Adept, a feat tree that only oni of the yai ancestries can take. It represents maverick oni who focus heavily on developing the elemental powers of their subspecies. But the path they walk is full of temptation, for the element of void plays upon negative emotions and can cause them to fall down a similar path not to the one they took with their evil former patron.
The Yai Adept feat tree begins with Yai Adept Dedication, granting them the benefits of the Third Eye feat, and if they already have said feat they increase the damage they deal with their eye lasers. They have 15 further feats to choose from spanning various levels, many of which have their own prerequisites on top of the base Yai Adept Dedication. They include such options as Distant Missiles (increase the attack range of their Third Eye), Focused Missile (can spend a bonus action/additional actions depending on system to "charge up" a more powerful attack with their Third Eye in the form of greater range increment and damage), Impaling Push (can make a melee attack dealing slashing or piercing damage that deals damage and causes forced movement and grapple in D&D or persistent bleed damage and possibly off-guard in Pathfinder), Towering Yai (permanently become Huge size), and Yai's Reprisal (deals a weapon or Third Eye attack as a reaction to a nearby foe that can disrupt the intended action on a critical hit). Each yai subspecies also gets a special feat to use in conjunction with Focused Missile, imposing a debuff relevant to their element on top of the base effects.
But what of this sinister, mysterious Void? Well, its allure is represented as its own series of feats: Void Missile can make the Third Eye deal necrotic damage and disintegrates targets killed or knocked out by it. Void Form lets the oni take on an insubstantial form much like Gaseous Form or the feat of the same name,* along with bonuses on Stealth checks and related actions in Pathfinder. Void's Enervation increases the power of a Void Missile to make a creature take additional damage equal to their level in Pathfinder or twice their Challenge Rating in D&D on a failed Fortitude/Constitution save. And Void Trap lets the oni teleport away, leaving a miniature black hole in their original location that is a damaging AoE effect that draws in targets closer to it on a failed Strength/Fortitude save. As for the "temptation," it's corrupting effect is more of a role-play tool rather than having a baked-in penalty or "morality points" style subsystem. The major downside of Void feats is that necrotic is a commonly-resisted damage type in D&D.
*and an oni with that feat can retrain it.
Thoughts: First off, I like the idea of an elemental-focused oni supercharging their laser eye beams for more powerful effects. However, it is quite feat-intensive in both systems: even for Pathfinder, you're going to have to substitute quite a bit of class feats if you invest in it unless you're using the Free Archetype variant rule. Compare this to Nymph Queen, who has a broader array of powers both in and out of combat. There are some feats that don't play off of the eye beams, such as Towering Yai and Impaling Push, although they don't feel tightly connected to the elemental themes save perhaps in flavor text or being used in conjunction with unarmed attacks which eye beams count as.
Thoughts So Far: Overall I really like the oni in both flavor and as an ancestry, although I wish that yai adept wasn't so feat-intensive and the lower-level feats had more worthwhile options. The ancestry may need to take some special consideration to fit into some non-Golarion settings given their particularly specific divine origins, but that isn't too big of a setback.
Join us next time as we visit the faerie courts of the sidhe!