Base Class: Fighter
Extra Defence
At 3rd level when using a shield you can ad half of your proficiency bonus to your AC.
Charging Wall
At 7th level once per encounter while using a shield when you move into the same space as an enemy you don't provoke an opportunity attack and deal 1d8 plus your strength modifier plus or minus the number of size categories larger or smaller than the target you are. At 10th level when you do this they make dexterity check against 10 plus your proficiency bonus plus your strength modifier. On failed check they are knocked prone, on a successful check they aren't.
Reflective Shield
At 10th level when you use a shield and are subject to a check the caster takes half the damage you would take when you succeed if you fail they take no damage. At 15th level if you succeed against a status check they must make a check against it on a fail you count as the caster.
Mobile Cover
At 15th level when using a shield you count as in half cover for non-magical ranged attacks.
Group Cover
At 18th level allies with in 5ft of you can add you shield bonus to their AC.