The Magician's Kudan is the 9th chapter in Tsubasa: Reservoir Chronicle.
Syaoran, Fai and Kurogane follow the letter's instructions and head off to Hanshin Castle. Apparently, they need Mokona to be around them if they want to communicate because Mokona translates their different languages to let them understand each other.
Upon reaching the castle, they come upon a huge crowd of people. Syaoran steps up and asks who among them wrote the letter. A girl's voice from high above the castle answers back: Primera, a popular Hanshin idol, is the culprit.
Syaoran pleads with her to release Masayoshi and Mokona. Primera, under the impression that the boy she kidnapped (Masayoshi) is Syaoran, still challenges him to a battle before she'll let them go. As Syaoran is wondering how he'll be able to get up the castle, Fai volunteers to go. With the help of his kudan, Fai flies up to Primera to start the fight.
Primera unleashes the power of her kudan, and with a loud blast, Fai is hit.