Frigden

The Frigden is an ancient cave located deep within the Frozen Sea. It is a Primal Place of Power and the only one with any written words, of which the Genasi believe holds all the prophecies of the land.
In reality the cave is a point where the veil between the prime material and the Primeval chaos where the Primordials are held is thin and the denizens who guard the place over-hear and write down communications overheard from the Primordials below, ushered into their minds by the Harbinger entrapped.

History

The prison was opened when the Genasi allowed a Yushan group to enter, who were then tricked in to freeing Venbria, the Harbinger of Secrets.