Energy Substitution

You have studied/practiced a particular energy type so thoroughly you may now cast spells of other energy types, as the chosen energy type. 

Increase your spellcasting ability by 1.

Choose fire, cold, acid, lightning,  or thunder when you take this feat. Whenever you cast a spell that does fire, cold, acid, lightning, or thunder damage, you may have it do the chosen damage type instead. Any extra effects of the spell (burn, paralysis, stun, etc.)can be modified or negated at the DM's discretion.

If a spell would deal the chosen energy damage type normally, without being modified by this feat, you may add your proficiency modifier to the chosen energy damage.

You may take this feat multiple times. Each time you take this feat, you must choose an energy type you have not chosen previously with this feat.