Dragon Clan of Yden. The Yden Trilogy, #2

As Jon's formal magical training begins, his budding romantic attraction to Kira jeopardizes his relationship with Brett. At the same time, the Dragon Clan is bringing the Earth-born children of Yden's wizards back home. Unfortunately, the Fox Clan has also been recruiting these teen wizards for its own sinister plans. The mysterious Guinn of the Fox Clan is searching for a weapon known as the Portal Key and is more than willing to kill for it.
Jon becomes increasingly desperate and reckless in his quest to thwart the Fox Clan, but he discovers-too late-his enemy is closer than he thinks.