Bulwark

The best offense is a good defense, especially if you can hit your enemies with that defense. Welcome to the bulwark, a rampart of absolute defense, beating foes by letting them tire themselves out against your iron tower, or using that iron tower to bash their face in.

Shield Bash

You can now bash your enemies with any shield from a plank of wood to a tower of steel.

You gain proficiency in Shield Bashing, if you have a shield equipped, it functions like a weapon dealing 1d6 bludgeoning damage using your strength modifier.
The damage increases to 1d8 at 7th level and 1d10 at 12th level.

One Man Phalanx

You assume a defensive stance becoming a one man phalanx. You can spend your action to plant your shield in front of you, your move speed becomes 0, you gain a +3 bonus to your armor class, you gain advantage on strength saving throws, and anybody that stands within 5ft. behind you, gains half cover. While in this stance, you can't use your action or bonus action to attack, you also can't use an attack of opportunity, however, the creature that is within 5ft. behind you can use their reaction for an attack of opportunity if you would normally be able to get an attack of opportunity. You can use bonus action to get out of this stance losing all effects of the ability.

Master of the Wall

You learn either the Protection fighting style, or the Defense fighting style.

Defense

While you are wearing armor, you gain a +1 bonus to AC.

Protection

While wielding a shield and a creature you can see attacks a target other than you within 5 ft., you can use your reaction to impose disadvantage on the attack roll.

Tough Target

You gain resistance to bludgeoning, piercing, and slashing damage. Yes, even magical.

Throwing Your Weight

You have learned how to use the weight of your shield and armor to your advantage, adding to the impact of your attack. Once per long rest, if you make an attack roll, you can use your reaction to add half your armor class ( rounded down ) to the attack modifier. You have to use this ability before you know if the attack landed or not. If the attack lands, you can add 1/4 of your armor class ( rounded down ) to the damage of the attack. You gain the ability back after a long rest.