The Fires of Hephaestus. The Starsea Cycle, #6

The Worlds will never be the same... The Swarmers are on the move. As star systems fall one by one, the League of Worlds begins to fragment. The Dread Pirate Zheng Yang advances her Golden Armada toward the League's core, bringing either death or salvation. The Prophet Sharo Khalin consolidates a theocracy in the spinward mid-worlds, while the League of Worlds concentrates everything toward a last-ditch defense against the Swarmers.
But unknown to all these major players, the Worlds' only hope lies in Lucian Abrantes, his crew, their starship, and of course, the powerful Orbs of Starsea. But even these powerful artifacts might not be enough to survive the dark days ahead. He must reach the hellish planet of Hephaestus before his enemies do, and claim the Orb of Thermalism, located somewhere on its lava-ridden surface. Can Lucian secure the prize, or will enemies old and new stop him in his tracks?