The mirror image spell is a nice way for magic users to hide from attacks. In a flash, three additional images all appear and move around the character. The images help deflect damage away, allowing one to live longer!
The illusion images do exactly what the character does, but do no damage nor take actual actions. These duplicates protect against physical and magical attacks.
Luckily, AOE spells that require a save wont take all of your duplicates out at once. -those only damage the character.
DM tip – a creature with blindsight or truesight will see through the illusion and attack the character directly – the duplicates wont help then.