Illumination is the rush of divinity the Gods pour into the world at Stonewake. Blessings and power meant to last until the next decade descent. It also refers to the storage of this divine power in Blackstone as well as other standard items of worship and prayer.
Blackstone is the basalt-like stone of Mount Steradian. It holds Illumination well and is the common magic resource: walls, roads, harvests, hearths, cantrips. Mined after Stonewake, spent over the decade, hauled back to be renewed. Nations rise and fall on its supply.