Pyrosia Rising

In the cliff-built city of Syracis, night is a killing ground. Ships vanish on black water, alleys are ruled by shadows, and the sea is a god no one argues with.
Daelios, a wall-born apprentice with a mind full of lines and angles, wants only one thing: fewer stupid deaths. When he learns to tame Pyrosia, a strange stone that burns clean and bright if handled exactly right, he believes he's found a way to give sailors back the horizon.
His sunboards and night guides quietly transform the coast. Ships steer truer. Streets grow safer under new blue fire. The navy sees a strategic revolution. The temple sees an omen that must be watched. And across the gulf, the richer, ruthless city of Kyros sees something else entirely:
A weapon they don't yet control.
As spies blunder through markets, priests argue over heresy, and admirals redraw their maps, Daelios fights to wrap rules around a force that refuses simple ownership: devices sworn never to be weapons, Pyrosia that must not burn hotter, and tests that must never leave the harbour. But every miracle creates hunger. Every new light throws a longer shadow.
All it will take is one missing shard, one copied diagram, one "accident" at sea—and the stone that was meant to guide ships home will teach empires how to end cities.
If he fails, Syracis becomes the proving ground for a war of faith and craft.
If he succeeds, he may only be proving that some discoveries can't be kept safe at all.
Pyrosia Rising is the first book in The Fire Between Worlds, a low-magic, high-tension fantasy trilogy about invention, faith, and the cost of keeping people alive in a world that wants their miracles for war.