Adonalsium

Adonalsium is a central fictional entity in Brandon Sanderson's Cosmere universe. It refers to the original god-like ruler who presided over a planet and its associated system of worlds. The Shattering of Adonalsium, an event of immense consequence within the Cosmere, divided his power into sixteen Shards—fragments of Adonalsium's essence—each embodying a particular aspect of his nature and its corresponding magic. After the Shattering, these Shards were taken up by individuals or bound to objects, becoming investitures that empower magic on many worlds.

A Shard can be held by a Vessel (a person or creature who bears the Shard's power) or exist as a splinter bound to artifacts. Over the Cosmere, Shards shape diverse magical systems. Examples include Harmony, a fused Shard formed from Preservation and Ruin that governs Scadrial's magic; Honor and Cultivation contributing to the magic of Roshar; Endowment upholding Awakening on Nalthis; Devotion and Dominion shaping segments of Sel's magic system; Autonomy influencing Shardic presence on Taldain. The history of Adonalsium's Shards is deeply intertwined with the political, religious, and cultural developments of many worlds, and the Shattering remains a foundational backstory for the Cosmere's cosmology.

In sum, Adonalsium's legacy is the sixteen Shards—powerful splinters of its former self—that continue to drive magic, conflict, and alliance across multiple planets within the Cosmere.