Way of Shirai-Ryu

Monks of the Way of Infernal Assassin follow a tradition that values stealth and subterfuge. These monks might be called ninjas or shadowdancers, and they serve as spies and assassins. Sometimes the members of a ninja monastery are family members, forming a clan sworn to secrecy about their arts and missions. Other monasteries are more like thieves’ guilds, hiring out their services to nobles, rich merchants, or anyone else who can pay their fees. Regardless of their methods, the heads of these monasteries expect the unquestioning obedience of their students.

Shadow Demon Arts

Starting when you choose this tradition at 3rd level, you can use your ki to duplicate the effects of certain spells. As an action, you can spend 2 ki points to cast darkness, absorb elements, flame blade, flaming sphere, [spell]pass without trace[/spell], or silence, without providing material components. Additionally, you gain the fire bolt cantrip if you don’t already know it. Whenever you take the Attack action you can forgo one of your unarmed strikes on your turn to cast fire bolt. You can spend 1 ki point to cast it twice as a bonus action.

Demonic Disciple

When you choose this tradition at 3rd level, you learn to mimic the speech and mannerisms of devils, granting you the following benefits.

• You learn to speak, read, and write Infernal.
• You gain proficiency in Intimidation (Charisma) and Sleight of Hand (Dexterity )if you are not already proficient. You have advantage on Stealth checks in dim or dark light.
• You gain superior darkvision with a range of 60 feet. At 9th level your vision borders the ethereal and material planes, you gain truesight with a range of 60 feet.

Kyton’s Grasp

You gain a natural weapon that takes on the appearance of a blade affixed to a long chain, which you can use to make unarmed strikes. This natural weapon has the reach property and counts as a monk weapon for you. You are proficient with it, and you add your Dexterity modifier to its attack and damage rolls. Its damage is piercing, and its damage die is a d4. This die changes as you gain monk levels, as shown in the Martial Arts column of the Monk table.

After hitting an attack with a Rope Dart you can attempt to pull the target closer to you. The target must make a Strength save vs your Ki DC or a contested Strength Check (Your Choice) or be pulled the full distance of the attack on fail. If target succeeds, the Rope Dart is pulled back to you. 

• Additionally, you can spend 1 Ki point to alter your attack. In a 5ft. radius around yourself, you can deal damage, as if a standard attack, with the Rope Dart to every creature in range.
• Outside of combat you can spend 1 Ki point to alter your blade for long distance travel extending its reach to 2 times your Monk Level.

Scorpions Blaze

At 6th level, you gain the ability to step from one hell portals into another. You now become capable of teleporting away in a fiery blaze. As a bonus action you can teleport anwhere up to 60 ft. You then have advantage on the first melee attack you make before the end of the turn. You can teleport a number of times equal to your proficiency bonus and regain uses on a short or long rest.

Hellish Visage

You gain resistance to fire damage. As a bonus action, you can expend 2 ki points to adopt your hellish visage, gaining the following benefits until you choose to end the effect or until 10 minutes have passed.

• The first time on each of your turns that you hit a creature and deal damage to it, you can deal an additional 1d6 fire damage to the creature.
• Fire damage dealt as a result of Hellish Visage and any of its benefits ignore resistance to fire damage

In addition to the previous benefits, when you activate Hellish Visage you choose three of the following benefits to gain for the duration.  Some benefits require you to be of a certain monk level.

Demon Dash. Whenever you use the Dash, Disengage action or, the Step of the Wind ki feature, you gain the ability to freely move through spaces occupied by other creatures, but you still cannot end your turn in another creature’s space. Any creature whose space you pass through must make a Dexterity saving throw, taking damage equal to one roll of your Martial Arts die, or half that damage on a success. Once a creature takes damage from this feature they cannot take damage from it again until the start of your next turn..

Hellport. Upon taking damage you can, as a reaction, expend 2 ki points to teleport to an unoccupied space you can see within 50 feet. Any creature within 10 feet of either the space you leave or the space you arrive in (your choice) must make a Dexterity saving throw or take fire damage equal to two of your Martial Arts dice.

Hellish Defense. Whenever you use the Patient Defense ki feature, any creature who attempts to make a melee attack against you before the start of your next turn must additionally make a Dexterity saving throw or take fire damage equal to one roll of your Martial Arts die.

Devil’s Reflection. Whenever you use the Deflect Missiles feature to reduce the damage of an incoming attack you may reduce the damage by an additional amount of d10’s equal to your half proficiency bonus (rounded up). If the damage is reduced to 0 and you expend a ki point to make the ranged attack specified by the feature, you can increase the damage by an additional 1d8 fire damage.

Fallen Ashes. When you use the Stunning Strike feature while Hellish Visage is active, if the creature fails the Constitution saving throw, the creature is also set aflame. The fire lasts for the duration of your Hellish Visage or until that creature or another creature takes a turn to douse the fire. The target takes fire damage equal to one of your martial dice at the start of each of the creature's turn. You must be 9th level to use this benefit.

Brutality. Whenever you reduce a creature to 0 hit points, creatures of your choice within 30 feet that can see you must make a Wisdom saving throw. On a failed save the creature immediately uses its reaction, if available, to move as far as its speed allows away from you. The creature doesn’t move into obviously dangerous ground, such as fire or a pit. A blinded creature automatically succeeds on the save. You must be 9th level to use this benefit.

Haunted Spear. When you hit a creature with an attack using Kyton’s Grasp, you can expend 1 ki point to make another attack roll against another creature within 10 feet of the original target. You must be 11th level to use this benefit.

Fatality

At 11th level you gain the ability to empower your strikes by inflicting pain.

Fatality. After hitting a creature with two consecutive melee attacks, the next successful attack against that creature made before the end of your turn is treated as if it were a natural 20.

Roving Assassin. Once per turn, if an attack you make with advantage hits a target, you can spend 1 ki point to deal 6d6 to that target.

Additionally, you don't need advantage on the attack roll if another enemy of the target is within 5 feet of it, that enemy isn't incapacitated, and you don't have disadvantage on the attack roll.

Once you use this feature, you can’t use it again until you finish a short or long rest.

Infernal Opportunist

At 17th level, you can exploit a creature’s momentary distraction when it is hit by an attack. Whenever a creature within 5 feet of you is hit by an attack made by a creature other than you, you can use your reaction to make a melee attack against that creature.

At 17th level you have become one with your demonic powers, allowing you to effortlessly assume your visage. You are permanently under the effects of your Hellish Visage. 

Additionally, your Hellish Visage also gains the following benefits in addition to the benefits already granted by the feature.

• Fire damage dealt as a result of Hellish Visage and any of its benefits deal half damage to targets with fire damage immunity.
• You gain immunity to fire damage while Hellish Visage is active. 
• You can spend 4 ki points to cast [spell]Wall of Fire[spell/] , [spell]Fire Storm[spell/] , [spell]Aganazzar’s Scorcher[spell/]