Way of the Dark Knight

Inspired by the abilities of Batman and Robin/Nightwing of DC Comics fame. This subclass allows a player to use many of the famous weapons and abilities that Dick Grayson and Bruce Wayne have used, and encourages the player to re-flavor other aspects of the monk class to suite the archetype as they wish. For example, the monk's stunning strike could become a stun rod instead. The ability to flavor this subclass more like Robin or more like Batman is available, as the level 17 feature allows you to embrace the role of either a team leader or a dark vigilante.

Stealth Acrobat

When you choose this tradition at 3rd level, you gain darkvision up to 60 feet if you don't already have it, as well as proficiency in Acrobatics.

Additionally, while you are in dim light or darkness, you have advantage on Stealth checks.

Utility Belt

Also at 3rd level, you gain a utility belt filled with useful gadgets. Your gadgets grant you the following abilities.

• Ninja Stars. You are a master at throwing stealthy weapons. Whenever you make a thrown attack with a dagger, its normal range becomes 40 feet for you.
• Grapple Gun. A one-handed device that allows you to move to high places with ease. As long as you have at least one hand free, your jump distance becomes 30 feet, with or without a running start.
• Smoke Pellets. These marble-sized pellets release clouds of vision-obscuring smoke when they impact a surface. You have a number of smoke pellets equal to your proficiency bonus, and can replace expended pellets at the end of a short or long rest. As a bonus action, you can toss any number of pellets at spaces on surfaces you can see within 30 feet of you. Each pellet then explodes into a 10-foot radius cloud of smoke, which dissipates at the end of the turn. The area inside the cloud is heavily obscured. Whenever you take the Dash or Disengage action, you can also toss smoke pellets as part of the same action.

Unconventional Upbringing

At 6th level, you are able to utilize the skills imparted to you by your unconventional training and upbringing.

Educated. You learn two languages of your choice. After you gain the Tongue of the Sun and Moon feature at 13th level, you can add a d4 to any Charisma checks you make at creatures who understand any of the non-Common languages you know outside of that feature.

Tactician. You gain proficiency in Investigation. As a bonus action, you can make an Investigation check contested by the Deception check of one creature you can see. On a success, you learn what the target's movement speeds are. On a failure, the target is immune to this feature until you complete a long rest.

Detective. If you have seen a creature before or know a creature's name, you can do research on that creature or creatures similar to it as part of a long rest, provided that you have access to written or spoken accounts of the creature where you are. You may only research one target each time you take a long rest. Make an Intelligence (Investigation) check as part of your rest. Based on the results of the check, you learn the following things about the target:

15 or above: You learn if the target has any significant allies or enemies in the local region.
20 or above: You also learn in which type of area the target (or its significant allies or enemies) would most likely be located (but not necessarily the exact locations).
25 or above: You also learn some steps that had been previously taken (if any) to combat the target which were unsuccessful.

Improved Gadgets

At 11th level, several abilities granted by your gadgets have improved.

Ninja Stars: Once per turn when you hit a creature with a ranged attack with a dagger, you can attach a wire to the weapon. If the target is Large or smaller, it must succeed on a Dexterity saving throw against your Ki save DC or be knocked prone.

Grapple Gun: Once per turn when you jump, your carrying capacity increases to 500 pounds until the end of the jump. This carrying capacity doesn't change if your Size category or Strength score changes.

World-Traveled Fighter

Starting at 11th level, your world-traveled martial training allows you to adapt to opponents in combat.

Once per turn when you hit a creature with an unarmed strike, you can deal additional damage to the target equal to one roll of your martial arts die. The additional damage can be any damage type of your choice.

Also when you take damage that isn't bludgeoning, piercing, or slashing damage, you can use your reaction to gain resistance to that damage type until the end of your next turn. You can use this reaction a number of times equal to your proficiency bonus, and you regain all uses of it when you complete a long rest.

Educated

After you gain the Tongue of the Sun and Moon feature at 13th level, you can add a d4 to any Charisma check you make at creatures who understand any of the non-Common languages you know outside of that feature.

Light vs Dark

When you reach 17th level in this class, you must choose a path for yourself: one as a team leader, or one as a dark vigilante. Each choice grants you different benefits.

Dark Vigilante

You have chosen the path of the dark vigilante, who strikes fear into the hearts of the lawless. You gain proficiency in Intimidation if you don't already have it, and while in dim light or darkness, you can take the Hide action as a bonus action.

Once per turn when you hit a creature with a weapon attack while you are hidden from it, you can to force the target to succeed on a Wisdom saving throw against your Ki save DC or become frightened of you. A frightened creature can repeat its saving throw at the end of each of its turns.

Team Leader

You've chosen the path of the team leader, who inspires their allies to work together and keep fighting. You and allies within 60 feet that can see or hear you have advantage on saving throws against the charmed or frightened conditions.

Also, whenever an ally within 60 feet of you fails a saving throw against a spell or other magical effect while you aren't incapacitated, you can grant that creature 5 temporary hit points (no action required) as long as they can still see or hear you after the effect.