While his confusion and misery deepened, Sargeras was forced to contend with a particularly insidious group intent on disrupting the Titans' order: the Nathrezim. This dark race of vampiric demons (also known as dreadlords) conquered a number of populated worlds by possessing their inhabitants and turning them to the shadow. The nefarious, scheming dreadlords turned whole nations against one another by manipulating them into unthinking hatred and mistrust. Sargeras defeated the Nathrezim easily, but their corruption affected him deeply.
As doubt and despair overwhelmed Sargeras' senses, he lost all faith not only in his mission, but also in the Titans' vision of an ordered universe.