The Heavenly Mandate is that power emanates from the heavens.
It's not just the Seven Fiend Tribulation. Whether it is 'Nature Master' or 'Ex Nihilo', their names inherently contain the source of their power.
According to An Jing's current understanding, the power of the Seven Fiend Tribulation originates from the Source of Great Tribulation of Heaven and Earth; the power of the Nature Master originates from the nature of all things; if not wrong, the power of Ex Nihilo likely comes directly from the primordial 'Embracing the Void Divine Wood', which is the power of creation from the void and the vacuum.
The most unique Lord of the World and Heaven and Earth Honor, their power should come from the living beings and order system within their dominion.
"In that case..."
An Jing contemplated as he raised his head, looking toward Da Chen's direction.
Indeed, there's some resemblance.