• Increase one ability score of your choice by 1. If you are a spellcaster, the chosen ability must not be your Spellcasting Ability.
• While you are not wearing any armor or wielding a shield, you Armor Class is equal to 10 + The Chosen Ability Score Modifier.
• If proficient with shield, they can wield their shield without losing the unarmored defense. 

As with all AC calculations, this calculation does not stack with any other calculation. If you already have, or gain the Unarmored Defense feature from another class, you choose which one to use (whichever gives you the higher AC).