Knights of Hades are incorporeal spirits that function in a similar fashion to the Mesmeri. They require a human host to interact with the world outside of Hades, and when within this human host they can be injured. Should their human bodies be destroyed, they recollect in the shape of essence and possess another. Their host body will not age, and is able ro reforge and recreate the armor unique to every Knight.
Each Knight is powerful alone, but their strength is increased dramatically when they are together. Knights of Hades, as their name suggests, prefer to fight in armor and with weapons that are demonic bastardizations of the weapons and armor used by orders of chivalry. They each ride a Nightmare of a specific color that corresponds to their attribute: white for Plague, red for Famine, black for War and pale for Death.