Counter Striker

You are trained to exploit the holes in your opponent's attack, granting you the following benefits:

• You can add your proficiency bonus to the damage dealt when you hit with an opportunity attack.
• If a creature misses you with a melee weapon attack, you can use your reaction to make an opportunity attack against that creature with advantage. Once you use this ability, you can’t use it again until you roll initiative at the start of combat or until you finish a short or long rest.