Oni: Iron Dominion

Oni: Iron Dominion is a monster supplement for 5e that presents oni not as chaotic brutes but as disciplined warlords of iron and hierarchy. Rather than treating oni as solitary monsters, this book frames them as a structured martial culture built on domination, command, and organized violence.

The intent of this product is mechanical clarity and encounter identity rather than simple stat escalation. The ladder progresses from CR 1 through CR 10, moving from brutal young enforcers to fortress-commanding tyrants. Each rung reinforces the central doctrine of oni warfare: hierarchy, intimidation, and coordinated brutality.

Oni forces are designed to function as organized warbands rather than scattered monsters. Lower ranks enforce strength through intimidation, while higher ranks project command auras that strengthen allied oni and punish weakness. An oni encounter should feel like facing a conquering army — disciplined, oppressive, and relentless.

Cultural lore and historical explanation are intentionally minimal. Whether these oni rule iron fortresses in volcanic mountains, command raiding armies across frontier lands, or dominate enslaved territories is left to the GM. These stat blocks are tools. The empire of iron is yours to define.

The Oni

Oni are tyrants of strength and command. Their society is built around rigid hierarchy where power determines authority and weakness invites destruction. From youth they are trained to dominate, intimidate, and enforce discipline through violence.

Oni encounters emphasize formation fighting, battlefield leadership, and coordinated assaults. Individual warriors are dangerous, but their true strength emerges when fighting under command. As oni leaders rise in rank, their presence reinforces allied resolve while crushing the courage of their enemies.

A force of oni should feel less like monsters and more like an invading army — organized, disciplined, and utterly confident in its right to rule.

Oni Roster

Oni Foundling (CR 1): Massive even in youth. Brutal enforcer-in-training who relies on raw strength and intimidation.  

Oni Exile (CR 2): Disgraced warrior hardened by survival who fights ruthlessly to reclaim honor through violence.  

Oni Raider (CR 4): Disciplined warband soldier wielding heavy iron weapons and targeting weak links in enemy lines.  

Oni Iron Adept (CR 6): Battlefield officer projecting commanding presence and reinforcing allied morale through fear.  

Oni War Captain (CR 8): Fortress commander maintaining strict formation discipline while coordinating devastating assaults.  

Oni Iron Tyrant (CR 10): Supreme warlord whose oppressive authority strengthens allied oni and dominates the battlefield.