Way of the Strangler King (5e Subclass)
From D&D Wiki
Way of the Strangler King
This subclass is designed to turn your average bare-handed fighter into a deadly weapon capable of choosing a guy and choking them into submission with grapples, this style is, admittedly, based on the character of Imai Cosmo from Kengan Asura
When you choose this archetype at 3rd level, you gain proficiency in Acrobatics. If you are already proficient with this skill, you gain expertise with it.
When grappled, you can try to strangle a creature. Make a melee weapon attack with your unarmed strike against the grappled creature. On a hit, you deal damage equal to your unarmed strike. The damage is bludgeoning.
At 6th level, when creature within 5 feet makes a melee attack against you, you can spend 2 ki points and use your reaction to make a grapple check with advantage against that creature. If you succeed, the attack misses and the creature is now grappled.
At 11th level, you can use your bonus action and spend 3 ki points to study an opponent's ki, to automatically know its next move. The DM must declare to the monk what the creature will do on his next turn.
- Determined Grappler
At 11th level, you can attempt to grapple bigger creatures by pinning their vital joints down such as shoulders, wrists, or elbows. You can now grapple creatures two sizes larger than you.
- The King of Stranglers
At 17th level, if you have a creature grappled, you may spend 6 ki points and use your action to perform a lethal maneuver. The target must make a Constitution saving throw (DC = 8 + your proficiency bonus + your Dexterity modifier). On a failure, the creature die instantly if it has 100 hit points or fewer. Instead of killing the creature, you can choose to knock the creature unconscious.
Otherwise, a creature with more than a 100 hit points will take damage equal to 10d10 on a failed saving throw, or half on a successful one. The damage is necrotic.