The Road of No Return.
This is a theoretically nonexistent yet practically existing path, which, once established, could lead anywhere.
And the Road of No Return leading to the deepest level underground was specifically constructed two hundred years ago as a passage, so that, even in the event the All Gods blocked it, the followers of the Dusk Cult could still find a way to communicate with the Flame Giant Surter.
Passing through the Road of No Return, a wave of heat hit instantly, and what entered the eyes was a vast void, where a giant seemingly made of flames and magma hung in mid-air by chains, its radiating light illuminating the cavity.
The Flame Giant Surter.
The King of Ash from the legends, whose mere existence could provide endless light and heat for the underground world.
Should he be released one day, the whole world would be pushed to the brink of destruction, everything would be burnt to ash.