And it was not darkness, but light-light, bright and pure as the sun on snow,...

And it was not darkness, but light-light, bright and pure as the sun on snow, that erupted from Asterin.
Light, as Asterin made the Yielding.
As the Thirteen, their broken bodies scattered around the tower in a near-circle, made the Yielding as well.
Light. They all burned with it. Radiated it.
Light that flowed from their souls, their fierce hearts as they gave themselves over to that power. Became incandescent with it.