Fiend Slayer

Your rage and hatred of Devils, Demons and all other creatures of the hells has made you more adaptive at fighting them and avoiding their tricks and attacks.

You gain the following benefits from this feat:

You gain advantage against all saving throws against all spells and spell effects that are caused by Fiends.

Fiends get disadvantage on saving throws that are caused by your attacks (Example: Stunning Strike, and Other Fighting Techniques or Spells)

Against Fiends only, when you roll an 18 or above on a d20 you make a critical hit either with a melee or ranged attack, or with a melee or ranged spell attack.