4th Level Feat, Spellcasting or Pact Magic Feature
Repeatable: Yes, but you must choose a different Damage Type each time for Energy Mastery
In your spellcasting, you can harness a particular form of energy with deadly mastery, granting you the following benefits:
Ability Score Increase. Increase your Intelligence, Wisdom, or Charisma score by 1, to a maximum of 20.
Energy Mastery. Choose one of the following Damage Types: Acid, Cold, Fire, Lightning, or Thunder. Spells you cast ignore Resistance to damage of the chosen type. In addition, when you roll damage for a Spell you cast that deals damage of that type, you can treat any 1 on adamage die as a 2.