The moon dragon is one of the many rare dragons, but it is fairly easy to get if you have the right dragons.
Here is the best options to use:
Ash + Snow
Mountain + Quake
Cold + Cactus
Iceberg + SonicThe incubation time for the moon dragon is 48 hours.
Description of the moon dragon from Dragonvale: The first mythical moon dragon was so enchanting that the first sun dragon created the world and stars for the two of them to share. But their magic was so strong that they had to separate themselves or risk destroying everything. Legend claims that they became the sun and moon and their descendants now live in our world.