Umbral Guard

calling on the power of the Shadowfell you guard yourself against harm. Until the spell ends you are wreathed in shadowy energy, you have a +3 bonus to AC including against the triggering attack, you have resistance to radiant damage, and Sunlight has no negative effect against you.

(only beings with a connection to undeath can cast this spell, such as vampires/Liches or necromancy wizards/ death domain clerics. ask your DM if your character is able to cast this spell)