Boon of the Furious Storm
Prerequisites 19th; Spellcasting or Pact Magic feature
You gain the following benefits.
Ability Score Increase. Increase your Intelligence, Wisdom, or Charisma by 1, to a maximum of 30.
Eye of the Storm. You have Resistance to Lightning and Thunder damage. While you are Bloodied, you have Immunity to Lightning and Thunder damage.
Storm’s Strength. Creatures have Disadvantage on saving throws against your spells that deal Lightning or Thunder damage.
Sources
Forgotten Realms: Heroes of Faerûn p. 43