The Final Trial - Royal Guide to Monster Slaying, Book 4

After discovering the reason for the monster migration, Rowan is on an expedition to prove that she is worthy of the ebony monster-slaying sword on her back. She, her twin brother, Rhydd, and their group are on a mission to help protect the dragon living in their homeland. But not everyone agrees that people can live peacefully with monsters. It will take everything Rowan has to fight off threats of all kinds, from both monsters and people. And if she succeeds, she will become Royal Monster Hunter at long last.