As a reaction, which you use when you are hit by an attack or missed by 4 or less, wispy flames wreath your body, shedding bright light in a 2-meter radius and dim light for an additional 2 meters. If the creature who damaged you is within 10 meters, it must make a Fortitude saving throw.
On a failure, it takes 2d8 fire damage and is burning 2.
On a critical failure, it takes twice as much damage and is burning 4.
On a success, it takes half as much damage and is burning 1.
On a critical success, it takes no damage.
You can increase the damage by 2d8 and the burning level by 2 for each additional mana expended.