Phalanx

You have trained to fight in disciplined shield walls and spear formations. Shield Drill

Ability Score Increase. Increase your Strength, Constiitution or Dexterity score by 1, to a maximum of 20.

Raise Shield
While wielding a heavy or versatile polearm with two hands, you can use a bonus action to brace your shield. Until the start of your next turn, you gain the AC bonus of a shield you are wearing. During this time, you are still considered to be wielding your weapon with two hands.

Shield Wall
While your shield is raised in this way, if you are within 5 feet of at least one willing creature that also has this feat and has its shield raised, attack rolls against either of you are made with disadvantage if the attacker is more than 5 feet away.

Hold the Line
As an action, you ready yourself against an advancing enemy. Until the start of your next turn, you can make one melee weapon attack against each creature that willingly enters your reach for the first time on a turn. These attacks do not count as opportunity attacks and do not expend your reaction. While this feature is active, you cannot make opportunity attacks until the start of your next turn.
You can use Hold the Line a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.