Age of Wonders 4: Thrones of Blood is a DLC for the turn-based strategy game Age of Wonders 4. It introduces a new vampire ruler type with a unique skill tree and city structures, replacing the Wizard's Tower with a Vampire's Castle. Players can also access three new Tomes of magic: Tome of Blood Rite, Tome of Torment, and Tome of the Crimson Reign, which grant new unit and spell abilities. The expansion includes a new story realm, the Sunless Lands, exploring the origins of Elder Vampires and featuring feuding guardians. New wildlife units such as Thorned Units, Blood Maggots, and various bats have been added, alongside new magic material Blood Glass and Ancient Wonders like the Crimson Fane and Rose-Choked Palace.