Knights of Arkyla: Sky Knight (Volume 1)

Book 1 of the Knights of Arkyla. Cassandra Bruen, lured into the world of dreams by an elf's trickery, is chosen to be one of ten Knights sworn to protect the land of Arkyla and an ancient alliance. But the peace that has lasted for centuries under the Knights' careful watch is threatened when one of their own order betrays them, and a dark prophecy casts its shadow over their desperate efforts to hold the kingdoms together.