Monks of the Way of the Prosthetic are recognisable by their use and mastery of a tool known as the Shinobi Prosthetic. These monks, through battle or through willing sacrifice, replace their left arm with this prosthetic, which acts as the centre for their combat and traversal. Prosthetic Monks might be members of a monastery, who craft their own prosthetics with their own hands before sacrificing one of them, or perhaps a unique warrior, Prosthetic handed down to them by someone equally as unique, tainted by the fires of hatred. 

Monks of this tradition typically take on the name of an animal, based on their combat style and general demeanour, such as Wolf or Orangutan. 

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Shinobi Prosthetic

Your arm has been replaced with a tool known as the Shinobi Prosthetic. You may utilise tools designed to attach to and work in harmony with your prosthetic arm.

At 3rd level, choose an arm to replace with the Shinobi Prosthetic. This hand must be empty to utilise the grappling hook and prosthetic tools. 

Gain the use of the grappling hook. Instead of moving conventionally, you may choose a point within range of your movement speed that you can see and that you can reasonably grapple onto, such as a tree branch, iron bars, or a gargoyle. You fire your grappling hook at this spot and pull yourself towards it rapidly, and however far you travel is counted as movement for this turn. You may choose a point even if it is above you, on a wall, or on a ceiling, but if you have nothing to hold on to when you reach your destination, you will fall and take fall damage as normal. Additionally, you provoke attacks of opportunity as normal, and taking damage while moving with the grappling hook causes you to lose your grip on the target surface and begin falling.

Additionally, choose one prosthetic tool to fit to your arm. When you gain a level in this class, you may choose a prosthetic tool you are using and replace it with another, if you so choose.

Divine Abduction

Prerequisite: 8th level in the Monk class

A Prosthetic Tool loaded with a large fan.

As a bonus action, you may use the fan attached to this Prosthetic Tool to shroud yourself in divine winds until the end of your next turn. If you take damage while shrouded in these winds, make a Constitution saving throw (DC 13). Upon failure, the winds disperse. 

At the start of your next turn, you may spend 1 ki point to release the winds in a maelstrom in a 5ft sphere centred on you. The first time any creature caught in this radius, it must make a Wisdom saving throw against your ki save DC. Upon failure, the creature is spirited away for a split second, and the next attack taken against that creature has advantage. Celestials and Fey have advantage on this Wisdom saving throw. 

The second time any creature is caught in the radius of Divine Abduction, they make a Wisdom saving throw against your ki save DC with advantage. Upon failure, the creature is spirited away to another realm and does not return. Celestials and Fey automatically succeed on this saving throw.

If you do not decide to cast the maelstrom, the winds disperse with no effect. 

Finger Whistle

Prerequisite: 6th level in the Monk class

A Prosthetic Tool created by fitting a slender finger to the prosthetic.

When within 30ft of a beast, spend 2 ki points as an action and force the beast to make a Wisdom saving throw against your ki save DC. Upon failure, the beast treats every creature as hostile for 1 minute. Upon success, they are immune to the effects of the Finger Whistle for 24 hours. 

The whistle can only affect one creature at a time. If you are within 30ft of multiple beasts, you must choose one to affect this way.

The Finger Whistle may also be blown as a bonus action without expending any ki points and used as a simple whistle. When blown this way, you may choose whether the sound is audible to one creature you can see within 150ft, or every creature within 300ft. 

Flame Vent

A Prosthetic Tool made from an iron barrel that spews fire. 

As a bonus action, spend 1 ki point to produce a 10ft cone of flame in front of you. Creatures in the affected area must make a Dexterity saving throw against your ki save DC. On failure, deal 2 martial arts damage dice + your Wisdom modifier fire damage, and half as much on success. 

Loaded Axe

Prerequisite: 12th level in the Monk class

A Prosthetic Tool loaded with a heavy axe that deals punishing blows. The strength of the Loaded Axe lies in its heft rather than its sharpness.

Immediately after you take the attack action, spend 2 ki points to make one melee weapon attack as a bonus action. This attack deals 4 martial arts damage die + your Dexterity modifier slashing damage.

Loaded Shuriken

A Prosthetic Tool created by fitting a Shuriken Wheel to the prosthetic. While it is palm-sized, a surprising number of shuriken can fit into the Shuriken Wheel 

When you make an unarmed strike attack, you may instead make that attack with a ranged monk weapon.

Loaded Spear

Prerequisite: 6th level in the Monk class

A Prosthetic Tool loaded with a horn-spear. The horn contracts to pull enemies in, also capable of stripping crude armour.

As a bonus action, spend 1 ki point to make an attack with the Loaded Spear. The Loaded Spear deals 2 martial arts damage die + your DEX modifier piercing damage and has a reach of 10ft. When you hit a creature with the Loaded Spear, you may spend 1 additional ki point to force the creature to make a Strength saving throw against your ki save DC. Upon failure, the creature is pulled 5ft closer towards you. If the creature is a larger size than you and is wearing armour, it instead loses 1 AC point as you strip some of the creature’s armour. A creature’s armour may only be stripped in this way once every 24 hours, and attempting to do so again will fail.

Loaded Umbrella

Prerequisite: 12th level in the Monk class 

A Prosthetic Tool created by fitting an indestructible iron-ribbed umbrella to the arm.

As an action, spend 1 ki point to deploy the umbrella until the start of your next turn. While the umbrella is deployed, gain +5 to your AC, your movement speed is halved, Dexterity saving throws are taken with disadvantage, and you cannot take reactions or spend ki points until the umbrella is collapsed. On subsequent turns you may use your action to keep the umbrella deployed at no additional ki point cost. 

If you are within 5ft of another creature, you may choose to make this creature protected. Protected creatures gain +5 to their AC while within 5ft of you. 

Mist Raven

A Prosthetic Tool loaded with the feather of a Mist Raven. Once you think you've caught one, all that will remain is feathers.

As a bonus action, take the Mist Raven stance until the start of your next turn.

When an attack hits you while in this stance, you may use your reaction to spend 1 ki point to negate the damage and teleport 10ft in any direction, shrouding yourself in smoke and leaving behind only feathers. You must choose to teleport before you learn how much damage you would take. 

If you use your reaction before taking damage, you make a Strength or Dexterity saving throw, or you take damage, you must break the stance and lose the chance to teleport, and lose the ability to teleport in this way until the start of your next turn. 

Sabimaru

Prerequisite: 8th level in the Monk class

A Prosthetic Tool made with an ancient shortsword, its blade mottled with bluish rust.

Immediately after you take the attack action, spend 2 ki points to make three melee weapon attacks as a bonus action. These attacks deal 1 martial arts damage die + your Dexterity modifier slashing damage and 1d4 poison damage. If all three of these attacks hit one creature, that creature must make a Constitution saving throw against your ki save DC. Upon failure, they are poisoned for 1 minute. At the end of each of their subsequent turns, the creature may repeat the Constitution saving throw and end the effect early upon success. 

Shinobi Firecracker

Prerequisite: 12th level in the Monk class

A Prosthetic Tool fitted with firecrackers.

As an action, spend 2 ki points to release a burst of firecrackers. Every creature in a 10ft radius who can see and hear you must make a Constitution saving throw against your ki save DC. Upon failure, the creatures are blinded and deafened until the end of your next turn or until they next take damage. The sound of the firecrackers is audible to every creature within 300ft.

Shinobi Deathblow

A shinobi is trained in the art of striking their enemy when they least expect. 

At 3rd level, when you hit a creature with an attack you had advantage on, expend 1 ki point to perform a Shinobi Deathblow.

When you perform a Shinobi Deathblow, roll a number of martial arts damage die equal to your proficiency modifier and add the result to your damage roll.

You do not need advantage on an attack to perform a Shinobi Deathblow if another enemy of the target is within 5ft of it, that enemy isn’t incapacitated, and you don’t have disadvantage on the roll.

Expanded Arsenal

At 6th level, you may select two prosthetic tools in the Shinobi Prosthetic ability.

You may only use one tool at a time, and may swap between useable tools as a bonus action, or whenever you spend one or more ki points.

At Higher Levels: Select a third prosthetic tool at 11th level. 

Breath of Life

At 6th level, when you successfully perform a Shinobi Deathblow, regain hit points equal to one martial arts damage die + your Wisdom modifier.

Expanded Arsenal: Improved

At 11th level, you may select three prosthetic tools in the Shinobi Prosthetic ability.

You may only use one tool at a time, and may swap between useable tools as a bonus action, or whenever you spend one or more ki points.

Fang and Blade

At 11th level, whenever you spend one or more ki points to use a prosthetic tool, you gain advantage on your next melee attack.

Ninjutsu

You have gained the use of ancient and magical combat techniques.

At 17th level, choose one Ninjutsu Technique to learn. Each technique can only be used after performing a successful Shinobi Deathblow.

Bestowal Technique

Ninjutsu technique that wreathes a blade in the victim's blood, extending its reach.

Spend 4 ki points to cause your melee attacks deal an additional 1d8 + your Dexterity modifier necrotic damage for 1 minute. 

Bloodsmoke Technique

Ninjutsu technique that turns the spraying blood of a victim to smoke.

Spend 4 ki points to create a 15ft sphere of smoke centred on the creature you hit with your Shinobi Deathblow to be heavily obscured. If another creature is caught in the smoke, you can use your reaction to immediately dash towards and make a melee attack against that creature. This smoke disperses at the end of your next turn. 

Puppeteer Technique

Ninjutsu technique that manipulates the victim like a puppet.

Spend 4 ki points to manipulate your target's mind. The creature hit by your Shinobi Deathblow must make a Wisdom saving throw against your ki save DC. Upon failure, you force the creature to become friendly and fight on your behalf for 1 minute. It gains temporary hit points equal to your proficiency modifier + your Wisdom score + your monk level. This technique works even if you reduce the creature to 0 HP. 

This effect lasts until the target loses all its temporary hit points, or 1 minute has passed. If the target was reduced to 0 HP, it will die when the effect is over. If not, it will become hostile again when the effect is over, aware it was under your influence. 

You cannot use the Puppeteer Technique on creatures with a challenge rating above your monk level. You can tell which creatures are vulnerable to the Puppeteer Technique by looking at them. Only one creature may be affected by the Puppeteer Technique at a time.