Publisher: Wizards of the Coast, 2021. Setting book for the Domains of Dread — a network of pocket-dimension horror realms, each shrouded in the Mists and ruled by a Darklord: a being magically imprisoned in and bound to their domain by the Dark Powers as both punishment and prison, tied to whatever sin or trauma defines them. Core domains include Barovia (Strahd von Zarovich), Bluetspur, Souragne, Kalakeri, Tepest, Karado, Hazlan, Falkovnia, and I’Cath, among others. The Mists can pull victims from any world, including Exandria, into a domain suited to their personal failings.
Reference: dnd.wizards.com