The Idoneth Deepkin are aelves who escaped from the belly of the god Slaanesh—but their souls were marked. To survive, they must steal the souls of other mortals. They live in underwater enclaves, hidden from the world, and their raids are like the tide—sudden, deadly, and inevitable.

Their armies are made up of Namarti infantry, Akhelian eel riders, Leviadons, and the mystical Isharann mages. They fight surrounded by the ethersea—a magical illusion of the ocean that accompanies them even on land. They are fast, elusive, and lethal. Their leader is Volturnos, prince of the Fuethán enclave.

The Idoneth Deepkin are isolated, mysterious, and tragically beautiful. Their culture is divided into castes—Akhelian warriors, Isharann priests and mages, and Namarti—the soul-incomplete, but brave. Their only goal is to survive... and everyone who stands against them will pay for it.