Elemental Adept Feat

Prerequisite: The ability to cast at least one spell

• When you gain this feat, 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 a damage die as a 2.
• You can select this feat multiple times. Each time you do so, you must choose a different damage type.

Source: PHB'14, page 166