Aaron & Keja: Time Dragon (Orgarlan Saga: Book 1)
The Elven Sorcerer, Lord Ky'debaul wants to kill a silver dragon to restore his magic powers.
This dragon is not just a silver dragon, it is a time dragon. But in order for him to do this, he must send the dragon to another world where it is not against the law to kill a Time Dragon. Here on Orgarlan, killing a Time Dragon is a Death Sentence.