Adaptable Mage Armor

You touch a willing creature who isn't wearing armor, and a protective magical force surrounds it until the spell ends. The target's base AC becomes 10 + your proficiency bonus + its Dexterity modifier. The spell ends if the target dons armor or if you dismiss the spell as an action.

This spell functions as an upgrade to the mage armor spell, ask your DM if you can take this spell. As an upgrade, this spell could be acquired through research and experimentation with the mage armor spell. I recommend treating this spell as a 5th level spell in terms of cost for research and development.