Flames of Avernus

You learn to call on hellfire to serve your commands.  You gain the following benefits:

• Increase your Intelligence or Charisma score by 1, to a maximum of 20.
• When you damage another creature with a spell that deals fire damage, you can dal an extra 1d8 fire damage to one target of that spell.
• Whenever you cast a spell that deals fire damage, you can cause flames to wreathe you until the end of your next turn.  The flames don't harm you or your possessions, and they shed bright light out to 30 feet and dim light for an additional 30 feet.  While the flames are present, any creature within 5 feet of you that hits you with a melee attack takes 1d8 fire damage.

You can select this feat multiple times.  Each time you do so, both damage rolls increase by 1d8.