C320 Heaven's Way Oven

By consuming the source energy of the Nine Layered Heavens, they would only be consuming their own lifespan. As a result, the nine great heavenly kings normally wouldn't use the source energy of the Nine Layered Heavens.

The ninth heaven, above the Divine City was the Ultimate Void. In the Ultimate Void was a furnace that had been burning from Immortal Ancient to this day