The City of Lost Souls. If you plan to make sequels, you can set it as: The Lost Realms Saga – Book 1, #1

For centuries, the legendary City of Lost Souls, Aethelgard, has hung over the desolate Cinder Wastes-a colossal, obsidian structure built entirely as a Soul Trap to harness the despair of the dead. Its perpetual, low hum is the sound of the world's growing sorrow, a silent source of power for the dark forces that wait in the Void. Elias, an ordinary cartographer's apprentice, only ever sought to be unremarkable.
But when an irresistible, icy pull draws him into Aethelgard's twisting, labyrinthine core, he discovers a terrifying truth: the glowing star-shaped mark on his palm is the Architect's Mark, a cursed, inherited sliver of the city's creator. Hunted by the lethal Cinder-Lords who seek to reabsorb his power, Elias is forced onto a desperate quest to reach the city's Heart and break the ancient Soul Binding.
He is joined by Lyra, an exiled warrior seeking penance, and guided by the Glint, a strange creature of light that is a fragment of the Architect's own guilt. As Elias navigates the terrifying Vein of Unmaking and learns to wield the chilling power to silence the city's energy flow, he undergoes a profound transformation from cartographer to Binder. But the ultimate cost of unbinding Aethelgard may be his own life, and the shattering of the Soul Trap threatens to unleash the greater, uncontainable terror of the Void upon a world unprepared for its endless darkness.
For centuries, the legendary City of Lost Souls, Aethelgard, has hung over the desolate Cinder Wastes-a colossal, obsidian structure built entirely as a Soul Trap to harness the despair of the dead. Its perpetual, low hum is the sound of the world's growing sorrow, a silent source of power for the dark forces that wait in the Void. Elias, an ordinary cartographer's apprentice, only ever sought to be unremarkable.
But when an irresistible, icy pull draws him into Aethelgard's twisting, labyrinthine core, he discovers a terrifying truth: the glowing star-shaped mark on his palm is the Architect's Mark, a cursed, inherited sliver of the city's creator. Hunted by the lethal Cinder-Lords who seek to reabsorb his power, Elias is forced onto a desperate quest to reach the city's Heart and break the ancient Soul Binding.
He is joined by Lyra, an exiled warrior seeking penance, and guided by the Glint, a strange creature of light that is a fragment of the Architect's own guilt. As Elias navigates the terrifying Vein of Unmaking and learns to wield the chilling power to silence the city's energy flow, he undergoes a profound transformation from cartographer to Binder. But the ultimate cost of unbinding Aethelgard may be his own life, and the shattering of the Soul Trap threatens to unleash the greater, uncontainable terror of the Void upon a world unprepared for its endless darkness.
The City of Lost Souls may be unmade, but the war for the Soul Binding has only just begun. The City of Lost Souls may be unmade, but the war for the Soul Binding has only just begun.