Basic Rules, pg. 275
Shield
1-level Abjuration
Casting Time: 1 reaction, which you take when you are hit by an attack or targeted by the magic missile spell
Range/Area: Self
Components: Verbal, Somatic
Duration: 1 Round
Attack/Save: Self
Damage/Effect: Warding
An invisible barrier of magical force appears and protects you. Until the start of your next turn, you have a +5 bonus to AC, including against the triggering attack, and you take no damage from magic missile.
Available for: Sorcerer, Wizard, The Hexblade, Artillerist, Battle Smith