The Perfect Insult

When a creature attacks you or casts a spell on you that applies negative effects, you can use a reaction and insult the creature that attacked you.

(Note: the creature has to be an intelligent creature. It cannot be a beast or an animal. Language does not matter, your insult will go through no matter what)

The creature that attacked you has to make a saving throw of 14 or higher in wisdom.

On a failed saving throw, you successfully demoralize the creature, and the creature has disadvantage on the current attack, and its next attack upon you. The insult has no effect if the creature chooses to attack or cast a spell on someone other than you. If the creature does not attack or cast a spell, but move instead, it moves at half its regular speed. 

You can only use this feat during a fight. You have one insult per fight. After you have insulted someone, you have no more insults to throw at people during that fight. When the fight ends, you regain your insult to use in the next fight.