Il'sariadh is an Eldar Craftworld.
In 116.M38, the Craftworld was visited by a large troupe of Harlequins, with the warrior-dancers pledging to assist them in their ongoing war against the Daemon-worshiping humans of the Villiad Collective. During the dazzling Harlequin dance performance that took place later, the Solitaire began to act strangely before suddenly catching another Harlequin on stage and breaking his neck. Cackling madly, the Solitaire revealed himself to be the Tzeentch Daemon known as the Changeling. The Changeling then went on to summon The Masque and a host of Slaaneshi Daemons inside the Craftworld. Though the arrival of the Craftworld's Aspect Warriors prevented a full-scale Daemonic invasion, Il'sariadh's effectively had its heart torn out during the battle due to the loss of its best and brightest.