Evoker's Exchange (Patreon)

Wondrous Item, uncommon

While wearing this amulet, you can choose to convert the damage from one form of raw energy to another. You can use this amulet as a spellcasting focus when you cast a spell of 1st-level or higher that deals only fire or lightning damage and doesn't require concentration. When you do, you can choose to have the spell deal lightning damage if it originally dealt fire, or fire damage if it originally dealt lightning.

If a spell that deals fire damage would normally ignite flammable objects that aren't being worn or carried, it does not if it's converted to lightning damage in this way. However, a spell that deals lightning damage does ignite such objects if it's converted to deal fire damage instead.

"Energy can't be lost or created: it can only be repurposed. I will be the one to decide what form it takes."