Shield Savant

Such is your prowess with your shield that you are able to inflict damage on your enemies with it. 

• If you take the Attack action on your turn, you can use a bonus action to ram your shield's rim into one of your enemy's painful parts. If you hit with this attack your opponent takes 1d4 bludgeoning damage. Your damage dice increases to 1d8 at Level 10 and 1d10 at level 15.
• If an ally you can see within 5 feet of you takes damage from an enemy creature within in range of your shield, you can use your reaction to attack the aggressor. Your damage dice is the same as your bonus action shield attack.
• If an ally within 5 feet of you is subjected to an effect that allows them to make a Dexterity saving throw to take only half damage, you can use your reaction to add the AC value of your shield to your ally's saving roll. If this intervention causes your ally to succeed on their saving throw, the creature causing the effect takes damage equal to the value of your bonus action shield attack, as a portion of that effect is deflected back at them due to your perfectly timed interposition. The damage type is the same as the effect you are protecting your ally from.