Buckler Expert

While wielding a buckler, you gain the benefit of being able to parry incoming attacks. 

Using 1 reaction you may attempt to parry an incoming attack by contesting the attack roll with a check that is Dex mod + proficiency bonus. If your roll beats the enemies by 5 or more than you parry the strike, causing the attack to miss, and opening the attacker up to an attack. You may now take an opportunity attack against the target.