Shield Expert

You've learned to use your shield offensively and defensively

• A bonus action each turn your can make an attack with your shield, you're are proficient and on a hit, deal D4 Bludgeoning damage + strength modifier or if you add a spike to your shield, piercing damage  
• In addition, if a friendly create within 5ft of you is subject to an attack you can use your reaction to add the shields AC bonus +2 to their defense, without negating yours.
• As an bonus action you can crouch behind your shield granting +3 to your AC, instead of the usual +2 to AC granted by a shield