The Guardians began to train Sera in the art of spirit-binding, teaching her the ancient rituals and the secret techniques. She learned how to create barriers, how to banish spirits, and how to control her own powers.She also learned about the Shadow Walkers, the elite members of the Obsidian Circle who possessed the ability to travel between the human world and the spirit world. They were powerful and dangerous, and they were the Circle's most valuable assets.One of the Guardians, a wizened old woman named Agatha, told Sera about her own encounter with a Shadow Walker years ago. She had been attacked, nearly killed, and left with a permanent scar on her soul.Agatha warned Sera that the Shadow Walkers were relentless, that they would stop at nothing to achieve their goals. She urged her to be careful, to trust no one, and to always be prepared for the worst.As Sera trained, she began to feel a change within herself. She was growing stronger, more confident, more powerful. She was no longer just a grieving daughter seeking answers; she was a guardian of the threshold, a warrior against the darkness