Ninja

Ninja/Kunoichi
Masters of the shadows! They are the night! Ninjas combine the monastic training of monks with the stealthy shenanigans of a rogue. Kunoichi are the female equivalent, and mostly the difference in the two is the kunoichi wears skimpier clothing.

Ki Training
The foundation of the Ninja's powers are cool acrobatic stunts. That most people will never see. At 8th level, the Ninja gains a number of Ki points equal to half their rogue level, and their unarmed attacks deal 1d4 damage, and can use their Dexterity mod instead of their Strength mod for attack rolls and damage rolls. The ninja has several ki abilities:
 * After using the attack action, the ninja can spend 1 ki to make an unarmed attack as a bonus action. If the ninja has advantage on the attack, they add their Wisdom modifier to the damage.
 * When making an attack when the Ninja would not qualify for sneak attack, they can spend 1 ki to add their sneak attack to the damage on a hit. They still cannot use sneak attack more than once per turn. If they use this function while they are capable of adding their sneak attack, they instead deal an extra 2d6 damage. This upgrades to 3d6 extra damage at 13th level, and 4d6 at 18th level.
 * As an action, the ninja can spend 3 ki to turn invisible until the end of their next turn, or until they make an attack.

Substitution Technique
The ninja is master of deception and theatricality! Also known as confounding enemies by pulling sudden nonsense out of their butts. At 13th level, the Ninja can use a reaction to spend 4 ki in response to being attacked to disappear, leaving a fake image of themselves. The attacking creature may attempt a DC (8 + Wis mod + Proficiency mod) Intelligence check to disbelieve this image after their attack, otherwise the believe the strike was successful. The ninja teleports up to half their speed away, and can make an immediate Stealth check to hide if they possess suitable cover to do so. The illusory duplicate vanishes at the start of the ninja's next turn.

Legendary Shadow
The ninja is a nightmare in human form! Or, really, they just deal in cheap hits. At 18th level, the ninja receives an extra 4 ki points, their unarmed damage is upgraded to 1d6, and whenever creatures are unaware of the ninja's location, they have vulnerability to his attacks.