The House of the Ten Chambers of Errestos is an arcane cult dedicated to unraveling mysteries mathematical and metamagical. Their membership is small and scattered throughout many places of learning both arcane and divine. The largest group of the Castellans of Ten Chambers live and work in the city of Kaldath where they have painstakingly assembled a physical reproduction of some of the interdimensional mathematics that they study.

Portal of the Elder Brain

The residents of the city have other names for the Ten Chambers of Esterros, generally referring to the cult members as “the brains” and their metamathematical temple-fortress as “the Portal of the Elder Brain” based on the rumours that the brains of the six eldest of the order have their brains pickled and built into the structure itself to power a failed gateway to another world.

The gateway, however, was not a failure (even if the fanciful…