Way of Baator

The Blood War is an epic and millennia-spanning battle between the evil forces of chaos and law - demons and devils - in a contest of raw fury and numbers against discipline and strategy. Monks of Baator are mortal servants trained to fight in such a war on the side of law, serving as scouts and infiltrators at lower levels and potent combatants to anchor key battles at higher levels. The only comfort known to a Monk of Baator, is that when death inevitably takes them, their soul is already sworn to rise in Baator as an advanced devil form to continue the fight in eternity.

Baatorian monasteries and schools where these techniques are taught can be found on multiple mortal worlds, and each layer of Baator. Many Monks of Baator join, form or even lead mortal cults - with Zariel, Dis and Levistus being the primary patrons of Baatorian monastic orders. Only the most powerful of mortal monks are permitted to attend the tiny cloister in Nessus, and nine are always stationed to guard Asmodeus' copy of the Pact Primeval in the citadel of Tabjari. See Mordenkainen's Tome of Foes pages 18-21 for descriptions and powers of diabolical cults.

Discipline and Eternal War

The first step on the Way of Baator is to recognize the discipline required to win an eternal war. To this end, the Baatorian monk must train in weapons and methods of warfare. Every Baatorian monk is taught to wield the trident and whip as symbols of diabolical authority, but is given latitude to train with other weapons not typical for monks to wield. You gain the Weapon Master feat and must select the whip and trident as two of your weapons. All weapons chosen via this feat count as monk weapons for you. Additionally, you gain a fighting style from the following list: Archery, Blind Fighting, Dueling, Thrown Weapon Fighting, or Two Weapon Fighting.

WEAPON MASTER
You have practiced extensively with a variety of weapons, gaining the following benefits:
Increase your Strength or Dexterity score by 1, to a maximum of 20.
You gain proficiency with four weapons of your choice.

FIGHTING STYLE
You adopt a particular style of fighting as your specialty. Choose one of the following options. You can't take a Fighting Style option more than once, even if you later
get to choose again.

Archery

You gain a +2 bonus to attack rolls you make with ranged weapons.

Blind Fighting

You have blindsight with a range of 10 feet. Within that range, you can effectively see anything that isn't behind total cover, even if you're blinded or in darkness. Moreover, you can see an invisible creature within that range, unless the creature successfully hides from you.

Dueling

When you are wielding a melee weapon in one hand and no other weapons, you gain a +2 bonus to damage rolls with that weapon,

Thrown Weapon Fighting

You can draw a weapon that has the thrown property as part of the attack you make with the weapon. In addition, when you hit with a ranged attack using a thrown weapon, you gain a +2 bonus to the damage roll.

Two Weapon Fighting

When you engage in two-weapon fighting, you can add your ability modifier to the damage of the second attack.

Force Multiplier

When you are struck it appears to your enemies that four rise in your place. Beginning at 6th level, whenever you take damage as a reaction you may cast Mirror Image upon yourself creating three illusory replicas of yourself to distract and confuse opponents. You must take a short or long rest before using this ability again. 

Additionally, you may choose a second fighting style to augment your combat prowess.

Archery

You gain a +2 bonus to attack rolls you make with ranged weapons.

Blind Fighting

You have blindsight with a range of 10 feet. Within that range, you can effectively see anything that isn't behind total cover, even if you're blinded or in darkness. Moreover, you can see an invisible creature within that range, unless the creature successfully hides from you.

Dueling

When you are wielding a melee weapon in one hand and to other weapons, you gain a +2 bonus to damage rolls with that weapon.

Thrown Weapon Fighting

You can draw a weapon that has the thrown property as part of the attack you make with the weapon. In addition, when you hit with a ranged attack using a thrown weapon, you gain a +2 bonus to the damage roll.

Two Weapon Fighting

When you engage in two-weapon fighting, you can add your ability modifier to the damage of the second attack.

Lawbreaker's Bindings

As a potent agent of law and retribution, you are able to immobilize agents of chaos and disorder, speaking commands in the language of Baatezu nobility: Mabrahoring, or High Infernal. At 11th level, as an action you can cast Hold Monster without material components on a target you can see who breaks a law or behaves chaotically (Beings of innate chaos such as Demons or Slaad can always be targeted) without material components. You can use this ability a number of times per long rest equal to your proficiency modifier.

Magistrate of the Nine Hells

As an advanced disciplinarian of the Baatorian order, your command carries a weight outdone by only the Archdevils. Beginning at 17th level, when you use your Lawbreaker's Bindings ability, you may cast Hold Monster as a 9th-level spell, affecting up to five targets simultaneously. This can be any five targets, not limited by action or alignment. Once you have used this ability, you cannot use it again until you complete a long rest.