Turambar

I think and hope its probably The Aztlanian.

But won't this theory mean that there is no point in being a nicrosil ferring. That is, if anyone in Scadrial can tap a nicrosilmind (I'm assuming that means they can both fill and empty it), then effectively everyone in Scadrial is a nicrosil ferring. The nicrosil ability of the ferring would only matter if he/she is a Twinborn in which case, people accessing their nicrosilminds can also gain the ability to burn the metal that he/she is a Twinborn of.