Vengeance! is the last Bloodlust sourcebook. It can be used without the other sourcebooks, since it adds a new continent to the game universe, with a much different setting.
The book describes in great details the continent of Vaeriel and its civilization, technologically advanced humans who use magic to power machines. It contains a lot of revelations about the past of the planet and the origins of the God Weapons, and twenty scenario ideas to be fleshed out by the gamemaster.