Deflect 2014

1st-level abjuration

Casting time: 1 reaction, you are hit by an attack or targeted by the magic missile spell
Range: Self
Components: V, S
Duration: 1 round
Classes: Sorcerer, Wizard

A transparent sphere of arcane force appears, averting incoming attacks. Until the start of your next turn, you have a +5 bonus to AC, to a maximum of 21 AC, including against the triggering attack, and you take no damage from magic missile.

At higher levels

When you cast this spell using a spell slot of 3rd level or higher, the bonus to AC (and the maximum AC) increases by 1 for every two slot levels above 1st (for example, when cast with a 5th-level spell slot, you have a +7 bonus to AC, to a maximum of 23 AC).

Source: Spells That Don't Suck (Somanyrobots) · License: Creative Commons Attribution 4.0 details