Defensive Duelist
Prerequisite: Dexterity 13 or higher
When you are wielding a finesse weapon with which you are proficient and another creature hits you with an attack that you can see, you can use your reaction to add your proficiency bonus to your AC for that attack.
If this causes the attack to miss you, you may also make a melee attack with a finesse weapon against that creature as a part of the same reaction if it is within reach.