An enemy armada invades! The heroes of New Horizon must launch their own forces to withstand the attack and eventually take the fight to the evil cult’s leader on the dark side of the moon. But to truly save their home, they must face the monster at the source of the deadly radiation threatening to kill every sentient creature in the system! This Starfinder Adventure Path volume concludes the Horizons of the Vast Adventure Path and includes: "The Culling Shadow," a Starfinder adventure for 11th-level characters, by Landon Winkler. Ways to continue your Horizons of the Vast campaign beyond the final fight, by Isis Wozniakowska. A toolbox featuring a description of the Negative Energy Plane, options for players to harness the power of that void, a collection of dangerous creatures, and a glimpse at a frozen, chalky world, by Iris Flanagan, Jenny Jarzabski, Georg Mir, Andrew Mullen, Hilary Moon Murphy, Dave Nelson, Jess Nevins, Thea Seals, and Landon Winkler. Statistics and deck plans for an AbadarCorp long-haul freighter, by Landon Winkler