Brawler / Rally Fighter

Normally reserved for those of the Monk lifestyle, close-quarter combat is their area of expertise with grace and skill. However, they are not beholden to the art of putting a fist into something's face. Brawlers are born from the pure desire of doing such a thing, forgoing the skill and grace of unarmed combat in exchange for raw overwhelming power.

Power of the Fist

At 3rd Level, you are proficient with unarmed fighting plus Improvised Weapons and your unarmed strikes deal 1d4 + Strength Modifier.

Your unarmed strikes deal more damage at higher levels 1d6 (7th), 1d8 (10th), 1d10 (15th), 1d12 (18th)

No Pain, No Gain

Also at 3rd-Level you can aggressively lunge forward to deal more damage at the loss of defense. On the start of an unarmed or improvised melee attack action you make, you can lower your AC by half your proficiency bonus (rounded down) to increase your damage by that same number for every attack you make that turn, this effect stays until your next turn. For example: If your Proficiency Bonus is +3, then your AC is reduced by -1 and your attack damage is increased by +1. 

Max increase is +3, Min increase is +1.

Sheer Willpower

At 7th Level your sheer force of physical power allows for your unarmed strikes and Improvised Weapon attacks to overcome nonmagical resistance and immunity. Additionally, should you enter combat without your Second Wind ability, you can use a bonus action to regain it. This can only be done once per long rest and upon entering initiative without the use of Second Wind.

Close-Quarter Bloodletting

As of 10th Level your body has become so brutalized by battle that you have a natural Unarmored Defense of 10 +  your Strength Modifier + your Constitution Modifier.

Additionally, if you use No Pain, No Gain while wearing no armor or using a shield, then your unarmed strikes and Improvised weapons deal an additional damage die of the attack so long as you are at or below half your hit points. If you take damage because of the use of No Pain, No Gain you can attempt to blind one creature within melee range using any melee attack you make on your next turn, you deal damage as normal even if the effect fails. The creature must make a Constitution saving throw to resist the effect.

DC = 8 + Strength Modifier + Proficiency Bonus

Didn't Hear No Bell

At 15th Level your stamina to stay in the fight is unmatched. Second Wind can no longer roll below 5 and should you receive a point of Exhaustion for any reason, you can resist it once per long rest. 

Haymaker

18th Level Brawler's are a force of nature not to be reckoned with. While using No Pain, No Gain during your attack action, you can reduce your AC by your full Proficiency Bonus to give yourself a +3 and Advantage for any attack's you make that turn. Should any attack be a critical hit apply the normal bonus from critical hits plus another additional damage die of your attack.

Only applies to two Critical Hits per turn.