Item from Malazan Book of the Fallen by Steven Erikson
Raest's soul container — an acorn-shaped vessel holding a Jaghut tyrant's power, a seed of apocalyptic potential that grew an Azath House when planted in Darujhistan.
The Finnest is a Jaghut soul-vessel: a container into which a Jaghut of sufficient power can place the core of their essence, preserving it separate from their physical form. Raest — a Jaghut tyrant of the old world, a being of power sufficient to challenge gods — placed his soul in this acorn before his imprisonment, and the Finnest survived his body's entombment. When the Finnest was brought to Darujhistan, it acted as a seed — drawing enough power to grow an Azath House that then imprisoned Raest permanently. The object's danger was never that it could be used as a weapon directly, but that it contained the complete magical identity of a being powerful enough to enslave continents. Anyone who cracked the Finnest would have released that power into the world without Raest's body to contain it — a magical detonation of incalculable scale.
A small, acorn-shaped object of dark wood or stone — unremarkable in size but radiating a cold that has nothing to do with temperature. The surface is smooth, almost organic. Holding it produces a sensation of vast, compressed power — like gripping a thunderstorm reduced to the size of a walnut.
Also known as: The Finnest, Finnest, Raest's soul container, the acorn