Chamber of Eventide

Deep within the Grand Palace of Hu'Xzoi is said to lie the Chamber of Eventide.
The Chamber of Eventide is an ancient device created by the Dawn Maidens to cleanse the emptiness from a person's soul. It lies within the Grand Palace of Hu'Xzoi. 
This accumulation of Emptiness in the chamber unintentionally exceeded the Keeper of the Apocalypse, so Selh'teus sealed it within himself to prevent Promathia from being resurrected.
It is possible the chamber used the divine light collected by the 5 towers in The Garden of Ru'Hmet.