Rank 1 Increases the damage done by your Fire spells by 1% per your Fire effects on the target, up to a maximum increase of 4%. Effects which mix multiple schools of magic do not qualify.
Rank 2 Increases the damage done by your Fire spells by 2% per your Fire effects on the target, up to a maximum increase of 8%. Effects which mix multiple schools of magic do not qualify.
Rank 3 Increases the damage done by your Fire spells by 3% per your Fire effects on the target, up to a maximum increase of 12%. Effects which mix multiple schools of magic do not qualify.