Source: Player's Handbook
1st-level abjuration
Casting Time:
1 reaction, which you take when you are hit by an attack or targeted by the
magic missile
spell
Range:
Self
Components:
V, S
Duration:
1 round
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 .