Oni 5e: A Guide to Shapeshifting Ogre Demons for Players & DMs

Nightmares made flesh and blood, Oni are terrifying boogeymen drawn straight from Japanese folklore into the pages of Dungeons & Dragons 5e

Played right, an Oni makes for a terrifying opponent, able to turn invisible, blanket their surroundings in magical darkness, and fly at will – not to mention cast a suite of powerful spells.

However, the Oni is more than a few spells and a nasty melee attack; their above-average intelligence and high mobility make them into dangerous ambush predators with the ability to stalk, observe, counter, and terrorize an adventuring party. 

Welcome to another creature feature, this time taking a closer look at the Oni, or Ogre Mage.

We’ll be giving you a breakdown of the Oni’s abilities, history, and how to approach them as both a player and a dungeon master. 

Oni

Large giant , lawful evil

Armor Class. 16 (Chain Mail)

Hit Points. 110 (13d10 + 39)

Speed. 30 ft., fly 30 ft.

STR: 19 (+4) DEX: 11 (+0) CON: 16 (+3) INT: 14 (+2) WIS: 12 (+1) CHA: 15 (+2)

Saving Throws. DEX +3, CON +6, WIS +4, CHA +5

Skills. Arcana +5, Deception +8, Perception +4

Senses. Darkvision 60 ft., Passive Perception 14

Languages. Common, Giant

CR. 7 (2,900 XP)

Proficiency Bonus. +3

Innate Spellcasting. The oni’s innate spellcasting ability is Charisma (spell save DC 13). The oni can innately cast the following spells, requiring no material components:

At will: darkness, invisibility

1/day each: charm person, cone of cold, gaseous form, sleep

Magic Weapons. The oni’s weapon attacks are magical.

Regeneration. The oni regains 10 hit points at the start of its turn if it has at least 1 hit point.

Actions

Multiattack. The oni makes two attacks, either with its claws or its glaive.

Claw (Oni Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) slashing damage.

Glaive. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) slashing damage, or 9 (1d10 + 4) slashing damage in Small or Medium form.

Change Shape. The oni can polymorph itself into a Small or Medium humanoid, into a Large giant, or back into its true form using an action. Other than its size, its statistics remain unchanged, regardless of its form.

When it polymorphs, the oni’s equipment remains unchanged, apart from its glaive, which shrinks so that it can be wielded in humanoid form.

If the oni dies, it reverts to its true form, and its glaive reverts to its normal size.

What Is an Oni in DnD 5e? 

Oni are hulking, demonic ogres with pale blue skin and a taste for humanoid flesh. They possess the ability to turn invisible and change their shape at will, allowing them to stalk their prey unseen before striking from within a cloud of unnatural darkness, finishing the fight with a blast of freezing magical wind.

Let’s break down the Oni’s stats and abilities in some more detail. 

First, Oni are smart. Their 14 Intelligence is enough to put them on relatively even footing with the average adventuring party. 

This means that the Oni is more than capable of using bait to lure adventurers into traps, assessing which party members pose the greatest threat, and avoiding tanky frontline fighters in favor of squishier spellcasters in the back, which it can reach by either turning invisible or just flying right over the frustrated barbarian’s head. 

Of course, that doesn’t mean that an Oni can’t go toe-to-toe with the party barbarian in single combat if it needs to.

This monster has a beastly 19 Strength, a solid AC of 16, and a respectable pool of more than 100 hp.

Still, it’s highly unlikely that an Oni will ever need to get into a stand-up brawl, much less fight to the death, equipped as it is with five different escape mechanisms: flight, at-will invisibility, at-will shapeshifting, at-will darkness, and gaseous form. 

Any party that walks up to an Oni in the open and expects to grind it down to 0 hit points by fighting fair is in for a rough day. 

This is especially true when you factor in the Oni’s regeneration, which allows it to heal itself by 10 hit points per round.

If an Oni is at 1 hp and manages to turn invisible or otherwise break out of combat with the PCs for as little as a minute, it can throw itself back into the fray basically at full strength again.

Oni History 

The Oni has existed as a monster in Dungeons & Dragons since the earliest days of the game.

It’s as old as the Beholder, with both of these monsters being introduced to D&D 1e as part of the game’s very first supplement, Greyhawk

These are properly Japanese Ogres, far more powerful than their Western cousins!

Gary Gygax, Rob Kuntz – Supplement I, Greyhawk (1976)

The Oni from the 1970s is actually remarkably similar to its 5e iteration.

Both can shapeshift, fly, and cast the Cone of Cold spell and are generally considered to be relatively faithful translations of the folklore from which the monster originates. 

In Japanese mythology, Oni are a type of otherworldly spirit (yokai) sometimes referred to as demons, ogres, goblins, or trolls.

They’re a stock villain in many traditional Japanese plays, often represented as tempters and tricksters who seem to get a great deal of joy out of messing with (or just eating) monks.

The meaning of their name is derived from the on’yomi reading of a Japanese character (隠) meaning “to hide or conceal.” 

Source: Sessen Doji Offering His Life to an Ogre (Japanese Oni), c. 1764 – Wikipedia (Public Domain)

Oni are also highly adept at using their above-average intelligence to use their Sleep and Charm Person abilities, both in and out of combat.

An Oni is 100% smart enough to recognize when it has brought the party’s rogue close enough to death to hit them with a Sleep spell or to take advantage of an isolated PC with a low wisdom save (sorry, Barbarian) and cast Charm Person.

What Does the Oni Want? 

An Oni’s motivations have two basic facets. Essentially, it wants to eat you and then steal your +1 Magic Sword

Drawing from their mythological roots, Oni eat people, animals, and each other.

A village or city with an Oni living nearby is likely experiencing a rash of strange disappearances – made even more puzzling by the fact the Oni likes to then steal the identities of its victims, covering its tracks while it plans its next kill. 

They’re D&D’s answer to Jeffrey Dahmer is what I’m saying. 

Oni also covet magical items and are sometimes found either working for evil wizards and hags or inserting themselves into unwitting communities in search of opportunities to steal magical artifacts or simply secure a steady supply of food. 

They’re intelligent and rational, capable of thinking strategically, setting traps, and manipulating those around them into being their unwitting servants.

They’re also cruel and malicious, enjoying the thrill of the chase, watching their chosen targets become increasingly paranoid as they accuse more and more random strangers of being Oni in disguise. 

A particularly cunning Oni could even insert itself into a position of local power, using its station in a town or city to both safeguard itself by diverting suspicion elsewhere and create new opportunities to feed. 

How Do I Fight an Oni? 

If you’re an adventurer looking to take down an Oni, careful planning is the name of the game.

Grinding an Oni down to its last few hit points only to have it escape and come back in a few minutes at full health is basically a death sentence for a lower-level party. 

Therefore, your plan should either be to drive the Oni away until you’re ready for a full-on fight (remember, this also gives the Oni more time to come up with a counterattack) or to trap it, slowly putting its abilities on cooldown until all you’re left with is a hulking, 8 foot-tall ogre with a big ax, regeneration, and the ability to turn invisible at will.

Piece of cake. 

First and foremost, you’ll need to pick the location for your battle carefully. Open spaces or areas with lots of exits are a no-go. You’ll want an enclosed space with minimal escape routes. 

Even then, an Oni’s gaseous form negates all but the most tightly sealed metal boxes.

This means you’ll either have to resign yourself to fighting the Oni until it burns this spell and then doing it all over again immediately afterwards unless you can spring some kind of trap. 

You’re also going to need some effective methods of counteracting the Oni’s magical darkness (the Light spell or Dispel Magic are both effective here), its flight (spells like Earthbind or just a big net perhaps), invisibility (low-level spells like Faerie Fire are great as they take advantage of the Oni’s mediocre Dexterity saving throw), and polymorph (secret passcodes, drawing Xs on people’s foreheads, making peace with “acceptable” civilian casualties and burning down the building – take your pick).  

Lastly, once you’ve exhausted the Oni’s various escape routes, you’ll still need to prepare yourself for a brutal fight against what’s more or less an ogre with a glaive.

Still, this is definitely the easiest bit. Just make sure you keep piling on the damage; you want to bring an Oni down in as few turns as possible so you aren’t wasting damage on its regeneration. 

One great way to stop an Oni regenerating hit points is to have someone repeatedly casting the Chill Touch cantrip.

While burning a simple d6 damage cantrip on an enemy every turn can feel underwhelming, the fact that Chill Touch prevents its target from regenerating any hit points on its subsequent turn means you’re actually dealing between 11 and 16 hit points of “damage” every time you land this spell on an Oni.

Pretty neat stuff. 

DM Guide: How To Run an Oni Encounter Like a Waking Nightmare 

Oni are easily one of my favorite monsters in all of D&D 5e for a few reasons: 

Interesting, Dynamic Combats

Monsters in D&D 5e designed to be used for solo encounters (aka without an accompanying hoard of minions like the Hobgoblin Warlord or Goblin Boss) tend toward being a big bag of hit points with multiattack (ahem, Red Dragon, ahem), which can turn combat into a mind-numbing war of attrition rather than an exciting combat. 

Oni, by contrast, are pretty weak where the action economy is concerned.

A CR 7 monster with two melee attacks per round is pretty lackluster on paper, but the Oni makes up for this with a huge toolkit of spells and abilities that make it a joy to run.

A mixture of high mobility, regeneration, debuffs, control, and escape abilities can make playing an Oni in combat challenging for a DM, but do it right, and you’ll end up running the kind of tense, dynamic battle both you and your players will remember for years to come. 

Survivability Doesn’t Just Mean Hit Points

Solo monsters in 5e tend to have a very short lifespan, as the fight tends to involve the entire party blowing all their high-level abilities on burning through a huge number of hit points, after which the monster is either dead or it uses its most powerful ability to knock down or maybe kill a PC.

Then, the surviving party members beat the monster to death and either revive their fallen comrade or say a quick prayer while the rogue goes through their pockets for loose change. 

Oni are survivable in a whole other way.

Their five different escape mechanics can make for an incredibly frustrating time for the PCs (in the best possible way), as they struggle to even hit their flying, invisible foe through a cloud of magical darkness and then stop it from turning invisible or into a fine mist before it hides and comes back again at full strength. 

Oni Are an Adventure in and of Themselves

Most solo monsters are good for an epic combat or a memorable random encounter – a hopefully engaging speed bump en route to a plot. 

Oni, however, are the adventure.

If you play an Oni right, you are going to give your players a multi-stage, spine-chilling horror adventure that fuels their paranoia, involves tense social encounters, and culminates in one or more epic battles against a foe they’ve come to fear and respect. 

Let’s take a look at how you can do that. 

Creating an Oni Adventure 

Let’s talk about making an Oni the central focus of an adventure. Used correctly, an Oni can organically create a plot with multiple stages: the mystery, the horror, and the final showdown. 

When your players begin this adventure, they should have no idea that they’re facing an Oni (or even what an Oni is, if possible).

Instead, they find themselves hired (or otherwise compelled) to investigate a series of disappearances in the local area. 

Recently, livestock started disappearing in the dead of night – showing up in the morning with large, jagged bites taken out of them, maybe even posed grotesquely or dragged up into trees to suggest a killer with immense strength and the power of flight, like a Griffon. 

Now, people have started going missing as well, although this is hard to prove.

The miller’s wife claims her husband has been missing for days, but the local guards saw him walking through town just this morning.

The mayor, freshly recovered from a horrible hunting trip in which the rest of his retinue were “eaten by bears,” loudly blames a local bandit gang, sending the PCs off to investigate.

A friendly local ranger carrying an ornate glaive offers to show you the way to their camp. More disappearances, even after the bandits are stopped. 

The PCs should be running around, gathering clues that point to all manner of different things.

Doppelgangers don’t eat people. Griffons wouldn’t come this close to the village. Someone would have seen. The Bandits were probably innocent. Maybe they weren’t even bandits. Why was the mayor so insistent they go after them? 

Showing up at the mayor’s house, it’s clear he hasn’t been home in days.

The stench of death hangs in the air, and the PCs quickly discover his body (several weeks old by now) stuffed into a closet. From the darkness, something demonic attacks. 

In the second “act of the adventure,” the players – fresh from their first encounter with the Oni – have to try and figure out what it is, how to fight it, and how to deal with the fact that the Oni is clearly messing with them directly. 

The Oni can impersonate anyone. It could rob the local store disguised as a PC, impersonate the head of the local temple to stir up conflict with the town’s thieves’ guild, or pose as a different kind of monster.

The possibilities are endless as long as you’re ramping up the players’ paranoia by using the Oni to act indirectly against the PCs, leveraging different factions against one another and the adventurers. 

In the final part of the adventure, the players should have gathered enough information or otherwise put enough pressure on the Oni to convince it that these busybodies need to be eliminated.

Either way, it’s time for a final showdown, where the Oni can bring all of its considerable bag of tricks to bear. It should be a memorable, horrifying fight. 

That’s it folks.

Hopefully, you should have a good idea of how to run an Oni adventure or, if you’re a player, survive an encounter with one.

Until next time, happy adventuring, and remember: trust no one, especially if they’re suddenly carrying a glaive.