Isles of the Emberdark

It helps but isn't strictly required. Isles of the Emberdark expands on the novella Sixth of the Dusk and includes its events as flashback chapters within the novel, so new readers can start here, though fans of the original novella will recognize returning characters and setting.

It's one of the latest Cosmere books, released after Wind and Truth (Stormlight Archive Book 5) in 2025 and set in the most advanced, far-future era of the Cosmere shown so far. It's best read after you're already familiar with the wider Cosmere, since it references earlier events and characters.

It's a standalone novel, and the fifth of Brandon Sanderson's "Secret Projects" — books written outside his announced schedule and funded through Dragonsteel Entertainment's crowdfunding campaigns. It also belongs to the wider Cosmere shared universe.