Nu-Mantia Intercept, Letter 7

What are the Stones?
The Stones are magical and physical echoes of the Zero Stone, by which a Tower might focus its energy to mold creation. Oftentimes, the Stones borrowed surplus creation from Oblivion, grafting it to the terrestrial domain of its anointed Tower.

It was and is difficult to bypass Oblivion to go directly to creation's source, the Aetherius. It has been done, but not without great expenditure, mundane and otherwise. However, access to Oblivion, the Void that surrounds Mundex Arena, which we might touch every night, was child's play in comparison.

Cultivating creatia that washed into the Void from Aetherius became the rule among Stones.

The Daedric Realms were formed on much the same principle: padomaic powers using aetherial refuse to build their void-territories. The Towers built on the Mundus, since the lands around them congealed in the absence of the gods, were unable to match the capriciousness of the Lords of Misrule.

Sometimes.

The Elves were dividing; some, like the Altmer, did their best to advocate "the will of Anuiel" and so embraced the chrysalis of the Convention; others, like the Chimer, refuted all orderings and aedric measures, following their prophet to "the Stone that is not a Stone that is." The most nefarious Tower, Walk-Brass, refuted even more, refuting unto dis-creation, but we shall come to its role in the present danger to Emperor Actual in a moment. It is but a lesser pawn to the greater evil:

The Tower of White-Gold, whose Stone is Chim-el Adabal, Amulet of Kings, whose masters are returning. I speak of course of the Ayleids, for which "sometimes" was not good enough.