Boon of the Furious Storm

Boon of the Furious Storm
Feat
Prerequisite: Level 19; Spellcasting

You gain the following benefits.
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.

Source: Forgotten Realms: Heroes of Faerûn (FRHoF), page 43