Thunder Dragon + Magician of Faith → Kaminari Attack

Thunder Dragon + Water Magician → Kairyu-shin

Thunder Dragon + Ice Water → Kairyu-shin

Thunder Dragon + Waterdragon Fairy → Kairyu-shin

Thunder Dragon + Ancient Elf → Kaminari Attack

Thunder Dragon + Water Girl → Kairyu-shin

Thunder Dragon + Metal Fish → Metal Dragon

Thunder Dragon + Mech Bass → Metal Dragon

Thunder Dragon + Aqua Dragon → Twin-headed Thunder Dragon

Thunder Dragon + Sea King Dragon → Twin-headed Thunder Dragon

Thunder Dragon + Turu-Purun → Kairyu-shin

Thunder Dragon + Guardian of the Sea → Kairyu-shin