The Void Realm, as described in ancient books, is a dark, silent, barren wasteland, but there are creatures there, and they are terrifying and powerful.

The void was originally an ancient and distant civilization, but it was inhabited by some creepy creatures. Among them are creatures of extraordinary intelligence who claim to be masters of the void, inheritors of the void civilization, simply because they are above the intelligence of other creatures.
In Valoran, however, they have another name: "watchmen".