Atium

Atium begins as the most coveted and mysterious of the Allomantic metals, a god-metal whose existence drives the Final Empire's economy and Kelsier's rebellion. Across the trilogy it transforms from a simple source of power into the literal condensed essence of Ruin, whose stockpiles and consumption become central to the fate of Scadrial itself. By the series' end, atium's true nature as both weapon and prison for a Shard is revealed, forcing characters to confront the moral cost of wielding divine power.