no one is safe from the twisting i am about to do 

Crippling Pain Below The Belt

At 17th level, the crippeling pain and agony caused by your attacks can hit beyond one’s body. Once per turn, you can expand 4 ki points to make one special melee attack against an opponent. If you hit the attack, the opponent must roll a wisdom saving throw against your ki save dc. If he fails, he suffers 6d10 force damage, and the following effects are applied to him:

• The creature becomes stunned, frightaned and falls prone, even if he is immune to these conditions.
• Every morning that creature must make the same saving throw. If it fails, it suffers 2d10 force damage.
• The creature can no longer reproduce, if it could before.

Hit 'Em Where it Hurts

Starting when you choose this tradition at 3rd level, you can make a deadly attack deadlier. When you score a critical hit with an attack that uses your martial arts or a monk weapon, you can roll one additional damage die. 

In addition, if the creature is exactly one size larger than you, your attacks become critical hits on 19. 

Blow Below The Belt

At 6th level, you improve your ability to manipulate your opponents’ body. When you use your Stunning Strike on a creature, you can expand 1 additional ki point to impose disadvantage on that creatures’ constituition saving throw. 

Protect Below The Belt

At 11th level, you learn how to keep yourself from harm's way and avoid devestating blows caused by your opponents. When an enemy lands a critical hit on you, you can use your reaction to expand 1 ki point and turn the attack into a regular one; it no longer hits automatically and deals regular damage.