"From the moment he could walk, Bowmark has trained for a fight to the death. The Disc awaits him: a giant bronze platform suspended over a river of lava. He dreads the day of proving—when he must kill or be killed—to claim the throne.
His people have hidden from the rest of the world for generations. But when the discovery of a mysterious Atlas reveals forgotten lands and peoples, Bowmark begins to question his culture's traditions and laws. His unavoidable future seems grim and pointless when contrasted with another world full of unique civilizations populated with other intelligent species and marvelous creatures.
Meanwhile new threats arise from the depths, hidden enemies emerge from within, and soon everything and everyone Bowmark knows and loves will be changed forever.
Torn between a desire to fulfill his duty, and his empathy for others, Bowmark must use all his intelligence and courage to navigate an uncertain future."
I read some of this book in beta. I really like it. Soon to be up at amazon. Here is her page.