Oni 5e: Stats, Regeneration, Spells and the 2024 Fiend

An oni is a CR 7 Large shapechanger with AC 16 and 110 hit points (AC 17 and 119 in 2024), a flying speed, Regeneration that restores 10 hit points every turn, and a short list of spells built for ambush: Invisibility, Darkness, Sleep, Charm Person and Gaseous Form. It can look like any Small or Medium humanoid, which is why it works best as a villain hiding in plain sight. In the 2014 rules it is a Giant with a glaive and Cone of Cold. In 2024 it becomes a Fiend with necrotic claws, a frightening Nightmare Ray and Invisibility as a bonus action, and loses Cone of Cold.

Table of Contents

• •Oni Stat Block (2014)
• •The Oni in the 2024 Rules
• •How the Oni Fights
• •Running an Oni Encounter
• •How Players Beat an Oni
• •Oni Encounter Ideas
• •Frequently Asked Questions

Oni Stat Block (2014)

This is the oni from SRD 5.1, matching the 2014 Monster Manual.

The pieces that define the 2014 oni:

• •Innate Spellcasting (Charisma, save DC 13). At will: Darkness and Invisibility. Once per day each: Charm Person, Cone of Cold, Gaseous Form and Sleep. It needs no material components, but casting is still an action and both at-will spells require concentration, so it can't hold Darkness and Invisibility at the same time.
• •Regeneration. It regains 10 hit points at the start of its turn if it has at least 1 hit point. Nothing in the 2014 stat block turns it off. No damage type stops it; the only answer is to finish it.
• •Change Shape. It polymorphs into a Small or Medium humanoid, a Large giant, or back to its true form, keeping its statistics. Its glaive shrinks with it, and a shrunken glaive deals 9 slashing damage instead of 15. If it dies, it reverts to its true form.
• •Magic Weapons. Its weapon attacks count as magical, so a creature's resistance to nonmagical bludgeoning, piercing and slashing damage doesn't reduce its glaive or claws.

The Oni in the 2024 Rules

The 2024 oni (SRD 5.2.1) keeps CR 7, its saves, skills and Regeneration, then changes what it is and how it attacks.

What changed at the table:

• •Invisibility every turn. The 2024 oni casts Invisibility as a bonus action. Invisible attackers have Advantage, and the spell ends right after the attack roll. So every turn the oni can turn invisible, make its first attack with Advantage, and make the second normally. Against AC 16, that first Claw goes from a 60% hit chance to 84%.
• •No Cone of Cold. The 2014 oni's one big area attack (8d8 cold, DC 13 Constitution) is gone. The 2024 oni deals its damage one target at a time.
• •It's a Fiend now. That brings it into range of a paladin's Divine Sense, Detect Evil and Good, and Protection from Evil and Good. In 2014, none of those notice or ward against an oni, because it's a Giant. This matters most for an oni disguised as a human: Shape-Shift keeps its game statistics, type included, so a 2024 paladin's Divine Sense names the friendly innkeeper as a Fiend.
• •Spells fit inside Multiattack. It can swap one attack for a spell, so it can claw once and drop Darkness or Sleep in the same action.

How the Oni Fights

Fight from disguise, not in the open. An oni's Deception is +8. It should meet the party as a friendly innkeeper or village elder, charm the most suspicious character, and choose when the fight starts: at night, when the party is split, after someone drinks the wine. Reverting to its true form costs an action. Do it before the reveal if you can, because a 2014 oni fighting in human form swings a shrunken glaive for 9 instead of 15.

Damage per round. Against AC 16, a +7 attack hits on 9 or higher, 60%.

Hit, vanish, heal. Regeneration makes retreat a weapon. A 2014 oni that drops below half hit points can cast Invisibility, fly 30 feet away, and recover 10 hit points every round it isn't found. Ten rounds is one minute and 100 hit points, close to a full heal. A party that lets it escape fights it again at full strength the next night.

Use Darkness carefully. Magical darkness blocks darkvision, including the oni's. Darkness works for the oni when it's escaping or splitting the party, not while it's trying to attack.

Sleep and Charm Person have different value by edition. The 2014 Sleep affects creatures by hit points (5d8, about 22), so against a level 7 party it only finishes off characters who are already badly hurt. The 2024 Sleep is a DC 13 Wisdom save in a 5-foot-radius sphere: one failure incapacitates a character until the end of its next turn, and a second failure knocks it unconscious, regardless of its hit points. Creatures that don't sleep, such as elves, automatically succeed. Charm Person targets Humanoids, so it works best before combat starts: the 2024 version cast at level 2 can charm two of them.

Fly away with the Nightmare Ray (2024). Hovering 30 feet up, out of melee reach, it can fire two rays a turn. Each hit leaves the target Frightened until the start of the oni's next turn, which gives the target Disadvantage on attack rolls and ability checks while the oni is within its line of sight.

Running an Oni Encounter

An oni is 2,900 XP.

Under the 2014 Dungeon Master's Guide guidelines (used by our encounter calculator), a lone oni is a Medium fight for four level 5 or 6 characters and Deadly for four level 4 characters. An oni with two ogres doubles to 7,600 adjusted XP, which is Deadly at level 7 and Hard at level 8.

Its real difficulty is not on the XP table. An oni that picks the time and place of the fight, opens with Sleep on the front-liner and retreats to regenerate is much harder than its CR. An oni that's caught in the open by a prepared party is easier.

How Players Beat an Oni

• •Burst it down. Regeneration only works if it has at least 1 hit point. Save the big damage for when it's low, and never let it end its turn out of sight.
• •Find the invisible oni. Faerie Fire stops an invisible creature from benefiting from invisibility. Flour on the floor, readied area spells and the 2024 Divine Sense (which gives its location) all help.
• •Unmask it. In 2024, Detect Evil and Good senses the location of any Fiend (among other types) within 30 feet, and Divine Sense tells a paladin both its location and that it's a Fiend. In 2014 the oni is a Giant, so those don't help; you need Insight checks against Deception +8, Detect Thoughts or a trap.
• •Banish the 2024 oni. Banishment is a Charisma save (+5). Against a 2024 Fiend, if the spell lasts a full minute, it doesn't come back. Against a 2014 oni, it returns when the spell ends.
• •Cold doesn't work well in 2024. The 2024 oni resists cold. Fire, radiant and force are untouched by any of its defenses.

Oni Encounter Ideas

The kindly healer. A mountain village's healer has adopted a string of orphans over the years. None of them stay long. They are always "sent to relatives in the city," and no letters ever come back. The healer is an oni in Medium humanoid form, and the village has gotten used to it. The party arrives because a traveler's child went to stay with him.

The night raids. A farming valley's livestock vanishes from locked barns. There is no trail. The oni flies in invisibly, carries off one animal, and regenerates any wounds from farmers' pitchforks before morning. A party that chases it into the woods finds itself hunted in the dark.

The ogre warlord. A band of ogres has started raiding with real tactics: night attacks, decoys, retreats. Their leader is an oni posing as a giant among them. Kill the oni and the ogres fall back into simple brutes, which the party can use as leverage.

Frequently Asked Questions

What CR is an oni in 5e?

An oni is CR 7 (2,900 XP) in both the 2014 and 2024 rules. It has AC 16 and 110 hit points in 2014, and AC 17 and 119 hit points in 2024.

How does the oni's Regeneration work?

It regains 10 hit points at the start of each of its turns as long as it has at least 1 hit point. Neither stat block lists a damage type that stops it, so the way to beat it is to reduce it to 0 hit points.

What spells can an oni cast?

In 2014: Darkness and Invisibility at will, and Charm Person, Cone of Cold, Gaseous Form and Sleep once per day each, with save DC 13. In 2024: Charm Person (level 2 version), Darkness, Gaseous Form and Sleep once per day each, plus Invisibility on itself as a bonus action.

Is an oni a giant or a fiend?

It's a Large Giant in the 2014 rules and a Large Fiend in the 2024 rules. That changes which spells and features detect or ward it, such as Divine Sense and Protection from Evil and Good.

Can an oni turn into a human?

Yes. Change Shape (2014) and Shape-Shift (2024) let it become a Small or Medium humanoid or a Large giant, keeping its statistics. In 2014 its glaive shrinks with it. In 2024 its equipment doesn't transform.

Stat blocks: System Reference Document 5.1 (2014) and 5.2.1 (2024), Wizards of the Coast, CC-BY-4.0. Tactics, encounter math and ideas are Loreify's own.