You have mastered the art of overwhelming your enemies with a barrage of rapid strikes, leaving them no time to react.
Flurry of Fists
You know that the best way to get through an enemy's guard is to overwhelm them.
At 3rd level, as a bonus action, you can spend a Combo Die and roll it to make a number of unarmed or Brawler Weapon attacks equal to half the number rolled (rounded up, minimum of 2 attacks). These attacks do not generate or lose Combo Die on successful hits or misses and do not add Punishing Strikes or modifiers to their damage. However, if all attacks hit, you regain the spent Combo Die.
Relentless Assault
At 6th level, your mastery of rapid strikes turns each attack into a building force of momentum, overwhelming even the most steadfast opponents. You gain the following benefits:
Strike Through Defenses: If you hit a creature with three or more unarmed or Brawler Weapon attacks during a single turn, they lose resistance to bludgeoning, slashing, or piercing damage until the start of your next turn. Additionally, you gain 2 Combo Die.
Momentum Precision: When you miss with an unarmed or Brawler Weapon attack, your next attack roll against the same target that turn gains advantage. If your Flurry of Fists hits with all attacks in a single use, you gain temporary hit points equal to your proficiency bonus.
No Opening, No Guard
Your attacks have become so rapid that enemies can't find an opening to strike back.
At 10th level, if you focus all of your unarmed or Brawler Weapon attacks on the same creature, that creature cannot use their reaction in response to your attacks, and they cannot make opportunity attacks against any creature until the start of your next turn. In exchange, you cannot make reactions this round. Additionally, if you land a critical hit during this round, you regain your reaction.
Chip Away
Your relentless attacks keep enemies on their heels and wear down their defenses.
At 14th level, if you land three or more unarmed or Brawler weapon attacks on a creature in a single turn, that creature suffers a -2 penalty to their AC and Dexterity Saves until the end of their next turn. This penalty increases to -3 if you land five or more attacks in the same turn.
Piecemeal Devastation
You've found a way to maintain the speed of your strikes without reducing their power.
At 18th level, your Flurry of Fists attacks now add your ability modifier and Punishing Strikes to their damage. Additionally, each successful hit with Flurry of Fists reduces the target's speed by 5 feet (cumulative) until the end of their next turn. If a creature's speed is reduced to 0 by this effect, they are also knocked prone.