You know how to fight while surrounded by foes and can quickly instruct an ally on how to move in concert to survive against an overwhelming number of foes.

Choose an ally within 5 feet. Until the start of your next turn, as long as that ally remains within 5 feet of you and is able to take actions, and both of you are unmounted, you and your ally increase your AC by 2. 

Watching a companion under attack infuriates you and you fling yourself at their opponent with a powerful shove.

After a creature within your reach makes a melee attack against an ally, you can use your reaction to make an Athletics check against the creature’s maneuver DC. On a success you shove the creature 10 feet away from you and you move 10 feet in that direction. 

Falling into step with a fellow warrior and putting both of your shields together makes each of you harder to hit.

While you are wielding a shield, you can choose one ally within 5 feet that is also wielding a shield. Until the start of your next turn, as long as that ally remains within 5 feet of you and is able to take actions both you and your ally increase your AC by 2.

You strike your foes in such a way as to leave an opening for your allies to follow-up.

Working in tandem with an ally, you fray the defenses of an opponent so your companion can better land a strike.

Choose a creature within your reach. The next ally within 20 feet that makes a melee weapon attack against that creature can use their bonus action to make an Athletics check against the target’s maneuver DC to grapple or push the target 10 feet.