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 a melee attack, you can use your reaction to add your proficiency bonus to your AC for that attack, potentially causing the attack to miss you.

Training Cost: 5,000 gp. Genie Coins: 500. Known Trainers: n/a. Key Ability: Dexterity