As a reaction, which you use when you are hit by an attack or missed by 4 or less, lightning lashes out from your body. If the creature who damaged you is within 10 meters, it must make a Reflex saving throw.
On a failure, it takes 2d10 lightning damage and can’t take reactions until the end of its next turn.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
You can increase the damage by 2d10 for each additional mana expended.