Mage Armor

Source: Player's Handbook

Level 1 Abjuration (Sorcerer, Wizard)

Casting Time: Action
Range: Touch
Components: V, S, M (a piece of cured leather)
Duration: 8 hours

You touch a willing creature who isn’t wearing armor. Until the spell ends, the target’s base AC becomes 13 plus its Dexterity modifier. The spell ends early if the target dons armor.