Thop's Barrier

When a creature hits you with a melee weapon attack or ranged spell attack, you can use your reaction to deflect the attack using a magical forcefield. Roll an ability check using your spellcasting modifier. The DC is equal to the attack roll total of the attack that hit you.
If you succeed, the attack is turned into a miss. If the attack was a melee weapon attack, the creature that hit you is stunned until the start of its next turn. While it is stunned, the next melee weapon attack that hits it is a critical hit.
If you fail the ability check, the damage you take from the attack is doubled.