Essence of Fire
This spell was originally developed by the Asahina to prevent magical tampering with iaijutsu duels. In the Crane view, iaijutsu is a test of the duelist’s own inherent skills and talents, and using the kami to aid in a duel violates its proper nature as the sacred judge of right and wrong. (The Crane also suspected certain other clans, such as the Scorpion and Dragon, of "cheating" with magic during duels.) This spell ensures that no magical effects will dilute the duel’s test of skill.