Protective Bulwark

When an allied creature is targeted by an attack from an attacker you can see, you can use your reaction to move up to half your movement speed to within 5 feet of your ally and switch places with them, and become the target instead. If you are wielding a weapon or a shield, you may subtract its weapon damage die (or 4 for a shield) plus your proficiency bonus from the damage.

You must use this reaction before you know whether the attack hits or not, and only a number of times equal to your Dexterity modifier. You regain all expended uses on a long rest, and if you have no uses left when you roll initiative, you regain one use.