The Cythai are the first Aelves who's souls were extracted from Slaanesh by Teclis. While he intended them to be noble, scholarly people's, something was terribly wrong with them. When confronted, they all collectively fled to where they knew Teclis' light could not reach; the bottom of the oceans. It is here they became known as the Idoneth Deepkin. As of the Age of Sigmar, only one true Cythai remains; Volturnos, of the Ionrach enclave.