Since the discovery that the Terrigen Mists-the key to unlocking an Inhuman's hidden potential and powers-are lethal to mutants, the X-Men and Inhumans have been locked in a cold war. But as the Terrigen seeps into the Earth and reaches an irreversible tipping point, the X-Men are spurred into action to ensure the future of their species! And for Jean Grey and Fantomex, this means taking out of commission the Inhumans' deadliest weapon: Karnak! Collecting: All-New X-Men #17-19, Annual #1, X-Men Prime #1