Fortress Knight

The archetypal Fortress Knight focuses on developing an impenetrable defense. While many close-ranged combatants think of their weapon as the most important tool they have available to them, a Fortress Knight's vital asset is their shield. Those who model themselves on this archetype combine immense physical hardiness with rigorous training in defensive maneuvers to defend themselves and their allies, from harm. 

The ideal Fortress Knight does everything in their power to guard their allies and charges from harm, using their body as a shield against all attackers, even if it costs them their life.

Pavise

Starting at 3rd level, when a creature you can see hits you with an attack, you can reduce the damage you would take by 1d8. You must be wearing a shield to use this feature.

Staunch Defender

Starting at 3rd level, when an ally within 5 feet of you takes damage, you can use your reaction to block the attack with your body, causing them to take no damage. Instead, you take the damage.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest. You must be wearing a shield to use this feature.

Defiant Defense

Starting at 7th level, while your Hit Points are below half of your current maximum, you can use your bonus action, to add your proficiency bonus to your AC until the start of your next turn. You must be wearing a shield to use this feature.

System Shock

Starting at 10th level, you gain the ability to capitalize on weaknesses in your opponents' defenses. When you deal 20 or more damage with attacks dealt during your action, you can use one of the following effects:

-Reduce your opponent's AC by 2 until the start of your next turn.

-You can make an additional attack with your bonus action.

-You can knock your opponent prone.

Punishing Strike

Starting at 15th level, when your opponent you can see within 5 feet makes an attack on you, and it misses, you can make an attack with advantage. You must be wearing a shield to use this benefit.

Penalty Shot

Starting at 18th level, when an ally within 15 feet is targeted for an attack, you can move to a space adjacent to their attacker and make a weapon attack. This movement does not provoke opportunity attacks. You must be wearing a shield to use this feature.