As a reaction, which you use when a creature that you can touch or see within 5 meters of you attacks you, you can try to divert the attack, provided that another creature is within the attack’s range. The attacker must succeed on a Will saving throw or it must target the creature that is closest to it, not including you or itself. If multiple creatures are closest, the attacker chooses which one to target.
You must choose to use this feature before knowing whether the attack hits or misses. Creatures that can’t be charmed are immune to this effect.