Way of the Pugilist

Fighting is what you were born to do. Hitting and getting hit drive you forward. Your interests don't lie in learning knowledge or worshiping your body, you just love the thrill of the fight. Survival is the only option and the only way to do that is to hit harder and faster than the other guy. You do anything you can to get the edge on your opponent, a thumb in the eye, an "illegal" sweep of the legs, a punch to the back of the skull. Rules are for competitions and on the street you don't need points, you just need to be the last one standing.

Perhaps you were raised on the streets, or perhaps you're a disgraced professional fighter, maybe your only source of release is underground street-fights. None of that matters, you fight to live but deep down you know you live to fight.

Fighting Dirty

Beginning at 3rd level you can spend a Ki point to do any of the following attacks:

Eye Gouge 
On your turn you can spend a Ki point and an attack to aim directly at your opponents eye. If the attack hits you deal an extra 1d4 damage and the opponent must make a Constitution save or be blinded until the end of their next turn.

Sweep the Leg
On your turn you can forego an attack and spend 1 Ki point to sweep at your opponents legs. The target must succeed on a dexterity save or be knocked prone.

Quick Jab
As a bonus action you can spend a Ki point to quickly jab at your enemy. The attack does damage equal to your martial arts die but does not add any proficiency bonuses. If the attack lands your next attack will be at advantage.

Tumble Technique

Starting at 6th level at the beginning of your turn you can choose a technique that best fits the current situation. 

Out-Boxer
If you choose this technique you can land a punch and slip away without consequences. As a bonus action you can spend a Ki point to enter an agile stance. During your turn, if you make a melee attack against a creature, that creature can't make opportunity attacks against you for the rest of your turn regardless of if the attack hits or not. You also have an additional 10ft of movement.

Counterpuncher
If you choose this technique you spend a Ki point and use an action to enter a defensive stance. You gain a +2 to your AC (Increasing by 2 every 4 levels). Should any enemy attacks miss you automatically retaliate with an attack of your own. If an enemy attack manages to hit you, you can use a reaction to retaliate instead. On subsequent hits you can spend an extra Ki point to retaliate.

If an enemy misses multiple attacks, you will automatically attack after each miss without spending a reaction. Counter Stance must be re-activated at the top of your turn. Counter Stance can be used in conjunction with Patient Defense. 

Slugger
You know how to take a punch and come back swinging. When you choose this technique, as a bonus action you spend a Ki point to plant yourself in one spot, reducing your speed to 0 as well as reducing the damage you take by 1d4. When in Slugger stance each enemy attack that hits will add an additional 1d4 to your next attack. Slugger must be reactivated with a bonus action every subsequent turn to continue to benefit from the stance. 

Twinkle Toes

At 11th level your reactionary footwork knows no bounds. When you hit a creature with an opportunity attack, you can spend a Ki point for one of the following benefits, as part of the same reaction:

Float Like a Butterfly: You follow your target up to your Unarmored Movement bonus.

Sting Like a Bee: You can attempt a second unarmed strike against your target.

K.O Punch

At 17th level you can use an action to spend 3 Ki points to unleash a devastating Knock Out punch. The punch deals 5d10 bludgeoning damage plus any bonuses. If a creature you target with this ability is brought below half their maximum Hit Points with this attack, they must make a Constitution saving throw or immediately be rendered unconscious. 

This punch can be used in conjunction with the Tumble Techniques.