as a str/dex based reaction, you deliver a swift punch reflexively an attacking creature within melee range or a projectile that crosses into your melee range, which will stun the melee attacker briefly (nullifying the attack, dealing an extra 1d12 bludgeoning damage to your unarmed strike and healing you 1d4+2 hp) or if its a projectile, it launches the projectile at any direction, dealing and extra 1d4 radiant damage and healing you 1d4 hp.