Flagbearer

The Flagbearer is an icon on the battlefield. The front line, the last bastion, a safeguard, and a conductor in his very own art. You gain Proficiency in 2 of 4 attributes: Intimidation, Persuasion, History, or Medicine.

The Flagbearer possesses a unique resource called Battleflow.
Battleflow accumulates whenever the Commander lands a melee weapon attack on an opponent.
You gain one point per hit. A natural 20 on the hit roll grants two points.

Flags. For a Flagbearer, a flag is indispensable, just as a Spell Focus is for a spellcaster or an instrument is for a musician...
A Flagbearer often uses weapons as flags at the same time... 

Any weapon that must be wielded with both hands (greatsword, great axe, halberd, spear) can also serve as a flag!
Alternatively, the commander may use a one-handed weapon with his dominant hand, but his other hand must hold a flag.

Flagbearer Features

The Flagbearer is an idol on the battlefield. The front line, the last bastion, a safeguard, and a conductor in his own unique art. You gain proficiency in 2 of 4 attributes: Intimidation, Persuasion, History, or Medicine. 

History

History

Intimidation

Intimidation

Medicine

Medicine

Persuasion

Persuasion

Battleflow

The Flagbearer has a unique resource called Battleflow.
Battleflow accumulates whenever the Commander lands a melee weapon attack on an opponent.
One point is awarded per hit. A natural 20 on a hit awards two points.

Flag Commands

Bolster Your Defense 
Your flag flutters inspiringly in the air. Your comrades strengthen their defenses.
Your allies within a 10-foot radius gain a bonus to their AC equal to half your proficiency bonus (rounded up) and a bonus to their saving throws equal to your proficiency bonus.
Lasts until the end of your turn 2 turns from now, Costs 2 Battleflow

Rally for Attack
You briefly plant your flag in the ground and give the command for a coordinated attack.
Your allies within a 10-foot radius gain a bonus to their attacks equal to half your proficiency bonus (rounded up) and deal damage (Force damage) equal to your proficiency bonus.
Lasts until the end of your turn 2 turns from now, Costs 2 Battleflow

Follow my Lead
You prepare to charge headlong into the fray on your own.
You gain a bonus to your attacks equal to half your proficiency bonus (rounded up) and a bonus to your AC equal to half your proficiency bonus (rounded up). 
Lasts until the end of your turn two turns from now, Costs 2 Battleflow

Onslaught

For each consecutive successful attack, you gain +2 damage (maximum +15) on your next attack.
If you miss your attack, the damage you deal through this ability is reduced by 4 (your damage cannot fall below the damage you would deal without this ability). 

Battle Commands

You can transfer your attacks to allies within a 10-foot radius; each ally may attack only once during your turn, gains Advantage on Attack Rolls, must make a Weapon Attack against an opponent of their choice, and thereby increases your Onslaught damage by 1—without reducing it on a miss—and increases your Battleflow by 1.
Doing so will count as an Attack within the Attack Action.
(The natural 20 rule does not apply here with regard to Battleflow.) 

Improved Flag Commands

The duration of your Flag Commands increases to 3 rounds.
“Follow My Lead” now also gains the damage bonus from “Rally for Attack” and the saving throw bonus from “Bolster Your Defense.”

Mastered Onslaught

If you land all your attacks during your turn (including Battle Commands), you may make one additional attack once per turn.