Arcane Armor (5e Feat)
From D&D Wiki
Prerequisites: The ability to cast at least one spell.
* When you use your action cast a spell of 1st level or higher, you can use your bonus action to surround yourself with arcane protection. When doing so, select a damage type from acid, cold, fire, lightning, or thunder. Whenever you take damage of the type you chose, it is reduced by an amount equal to your proficiency bonus. This effect lasts for 1 minute. Once you use this effect, you must finish a short rest before you can do so again.
- If you hit with a melee attack while your Arcane Armor is active, you can choose to end the effect early to add your proficiency bonus to the damage of this attack. This extra damage is of the same type as your Arcane Armor.