Pugilist

Knockout – When you score a critical hit with an Unarmed Strike against a target whose current hits points are less than half its maximum, the target must make a CON saving throw (DC = 8 + your proficiency bonus + you STR modifier*) or be knocked unconscious for one minute, dropping anything it is holding and falling prone. The target may repeat the saving throw at the beginning of each of its turns, regaining consciousness on a successful save.

*If you have an ability or class feature, such as the Monk's Martial Arts, that allows you to use DEX for your Unarmed Strikes, you may replace STR with DEX in the save DC calculation.

Haymaker – Before you make a melee attack with an Unarmed Strike, you can choose to take a -5 penalty to the attack roll. If the attack hits, you add +10 to the attack's damage. You may not make this attack against a creature you are currently grappling.