Steel Body (5e Feat)
From D&D Wiki
Prerequisites: Constitution 15 or higher
Your body has come to be as hard as steel, allowing you to glance blows like you have armor and hit like a train while in the nude.
- Your AC increases by +1.
- Your Unarmed Strikes are now equal to 1d4 + Strength or the Damage die of your Unarmed Strikes are now one die size bigger. (i.e. 1d4 -> 1d6)