PHB
Mage Armor
1-level Abjuration
Casting Time: 1 action
Range/Area: Touch
Components: V, S, M
Materials: a piece of cured leather
Duration: 8 hours
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 13 + its Dexterity modifier. The spell ends if the target dons armor or if you dismiss the spell as an action.