Welcome to the first in a new series of articles where we run through the lore of the Age of Sigmar factions.
These are intended to give you a little flavour into the faction, and hopefully give you an understanding on what drives them.
The World That Was
The story of the Idoneth begins way back in the world that was, right after the forces of chaos forced their way in, and right before they ultimately conquered it. During this time there was a sect of Aelves who worshipped the god known as Mathlann. God of both sea and storm and known as the lord of the Deep, Mathlann was primarily worshipped by sea fairing Aelves, and explorers. When the Chaos gods began to consume the souls of all living creatures, Mathlann sought to protect the few he could from them, and so he took a contingent of his followers and hid them at the deepest depths of the oceans. Despite this, Slaanesh could sense more souls still, and would root out each remote enclave one by one until every single aelvan soul was devoured.
The Age of Myth
During the age of Myth, what remained of the Aelvan pantheon awoke, and sadly Mathlann was not amongst those who survived. Teclis, Tyrion, and Malerion awoke in a world which lacked any Aelves to rule over, and as such devised a plan to capture Slaanesh and pry the souls from his gullet. Each of the three main gods would receive a share of the souls, and Teclis would be the first to receive them. Those souls which were first pulled from Slaanesh, turned out to be those of the idoneth. Those original souls would come to be known as the Cythai.
No Rest for the Wicked
After escaping both from Teclis and Slaanesh, the Cythai found themselves within the throes of a new horror. The combination of Corruption from Slaanesh, Purification ritual from Teclis, and the lack of a God to draw from led the majority of Idoneth to be born with Waning souls. Many of their offspring fail to live past infancy, and those that do (the Namarti) , have drastically shortened life spans. Some would be born with proper souls (Akhelians) and this disparity between the two would go on to form the basic structure of Idoneth society. To ensure their survival something would need to be done. Adapting the magic that Teclis had taught them they would form a new school of magic revolving around the removal of and transmutation of souls. Unfortunately, the souls of Sea life would not be enough to sustain that of an Idoneth body for any more than a couple of days, the only alternative was to seek out greater prey. The Idoneth would form raiding parties that would ascend from the depths raid coastal settlements taking with them the souls of the fallen back to their enclaves. To ensure secrecy, the Idoneth would weave spells to erase the memories of survivors.