You're Coming With Me
You know better than to let your opponents get away. At 3rd level, when you land an unarmed attack, you can spend your Bonus Action and one Combo Die to perform the grapple action. When you do so, roll the combo die and add the result to your check. Additionally, you can grapple creatures of any size. When you successfully grapple a creature, you can move them up to 10 feet in any direction without expending additional movement, and you have advantage on Strength (Athletics) checks made to maintain the grapple.
Iron Grip
At 6th level, your grip becomes unrelenting, and no one escapes your grasp easily. You gain the following benefits:
When a creature attempts to break free of your grapple, they roll their check with disadvantage.
When you succeed on a Strength (Athletics) check to initiate or maintain a grapple, you can impose one of the following conditions on the grappled creature until the grapple ends:
Hobbled: The creature’s movement speed is halved.
Weakened: The creature has disadvantage on Strength-based attack rolls and saving throws.
Dazed: The creature has disadvantage on Dexterity saving throws.
Additionally, you can maintain a grapple with one hand, allowing you to wield a Brawler weapon or make unarmed attacks with your free hand while keeping the creature restrained.
Suplex, Lock, and Throw
You're accustomed to fighting enemies close up and personal. At 10th level, when you're grappling an enemy, you can perform one of the following actions in place of an unarmed weapon attack on your turn.
Suplex: You can attempt to slam the enemy into the ground. The grappled creature must make a Strength Save versus your Brawl Save DC or take twice your unarmed damage and be knocked prone. Additionally, the creature is stunned until the start of your next turn. You can spend any number of Combo Die, increasing the Save DC by one for every two dice spent.
Lock: You firm your grasp on the enemy and put them into a lethal lock. The grappled creature must make a Dexterity Save versus your Brawl Save DC or become restrained. Additionally, at the start of the enemy's turn, they take 1d6 Bludgeoning Damage if they are still restrained in this way. This damage increases by 1d6 for each turn they are grappled, up to a maximum equal to your proficiency bonus. When the creature attempts or reattempts this save, you can spend one Combo Die to increase the Save DC by one.
Throw: You attempt to toss the grappled creature aside. The grappled creature must make a Strength Save versus your Brawl Save DC or be thrown a number of feet equal to your Strength modifier x 10 and take your unarmed damage. As a part of throwing the creature, you can spend a Combo Die and increase the distance thrown by 10 x half the die roll (rounded up). A creature two size categories or more larger than you has disadvantage on the roll.
Ground Fighting
At 14th level, you do not suffer from disadvantage when making unarmed attacks while prone. Additionally, when you are grappling a prone creature, you deal an additional die of damage with unarmed or Brawler weapon attacks and techniques. Furthermore, if a creature within 5 feet of you targets you with an attack while you are prone, you can use your reaction to make an unarmed strike against them with advantage.
Meat Shield
Why take damage when you have a nearby body to take it for you? At 18th level, if you would take damage while grappling a creature, you can use your reaction to redirect all of that damage to your grappled target. Additionally, you gain temporary hit points equal to half the damage redirected in this way. If the grappled creature is reduced to 0 hit points by this feature, you can immediately move up to half your speed and make an unarmed attack as part of the same reaction.