Mirror Shield

Armor (shield), rare Price: 1,000-10,000 gp | low sentimentality

The surface of this metal shield is so perfectly reflective that you can use it as a mirror. Your gaze is considered averted from a creature or object when you view its reflection in the shield.

Paid

With the shield in hand, when a spell that targets you and requires an attack roll misses you, you can use your reaction to reflect the spell back at the creature that attacked you. You make a ranged attack roll as part of the same reaction to determine if the reflected spell hits.

Overpaid

With the shield in hand, you gain a +2 bonus to saving throws against spells that require the target to make a saving throw to avoid some or all of a spell’s effects.

Source: The Gray Merchant of Asphodel