Cain's reaction mirrored that of the others in the hall—his eyes sharpened, his expression growing more solemn. A Demon King wasn't a race but a title given to an extremely powerful entity, typically from an enemy army.
If someone as powerful as Lady Alume referred to an entity as a Demon King, it implied that this being's strength could rival ancient life forms like the Star Bound Sovereign. Worse still, if this Demon King's castle lay inside the Primeval World, it might be connected to the Great War—a time in the Crimson World when even Void Eclipse-level entities perished on a daily basis.
Seeing that she had the full attention of every faction, Lady Alume continued, her voice commanding the room. "I know the Tiamat Sect and the Sun Church plan to rampage against each other the moment you enter the Primeval World, eager to settle your grievances within its confines. You hope to seize more treasures while weakening your opponent—a ruthless, bold, and very smart move."