The Monolith has been found in the Red Cathedral well in advance of our heroine, Agatha Heterodyne coming into power over Mechanicsburg by at least one fragment of the organization called The Knights of Jove. At least two members of which are the The Abbess of the Red Cathedral and Martellus von Blitzengaard. The purpose of this mysterious object is forming a connection with its counterpart to form a space-jump connection between the Red Cathedral and The Refuge of Storms.
It is indeed a plot changer because as the four characters fell through it and into The Refuge of Storms, Klaus activated the Take five device. This caused the Monolith to jump the quintet forward in time by thirty months or two-and-a-half years, which is referred to by fans as the Timeskip. The effort of retrieving these people the The Refuge Counterpart to .
Upon being told about how Agatha escaped Mechanicsburg, Zeetha immediately made a connection from it to a piece of Skifandr lore, ", a magic gate that the first Skifandr ancestors used to travel to their current home.