You have learned to fend off strikes directed at you, or other creatures nearby. If you or a creature you can see within 5 feet of you is hit by an attack, you can roll 1d8 as a reaction if you’re wielding a melee weapon or a shield. Roll the die, and add the number rolled to the target’s AC against that attack. If the attack still hits, the target has resistance against the attack’s damage.

You can use this feature a number of times equal to your Constitution modifier (minimum of once), and you regain all expended uses of it when you finish a long rest.