Unlike what Feng thought, the Soul-Devouring creature was treating Earth as a mere source point.
The grand plan wasn't to create a massive farm in which humans will be the cows, and what will be milked is the soul.
The Grand plan was something entirely else.
The grand plan was to use the humans on Earth to create an army. Those humans that join the side of evil and serves under the soul-devouring creature will be allowed to become the leader of one of the many legions. While those humans who had decided to fight back will be used to create Immortal-zombie and different types of zombies. As a plus, the SDC(Soul-devouring creature) will let the dogs serving under It to do whatever they want with the humans before and during the torture. This army-building plan has already taken effect in every human city, town, places, and area that is located in the Red-zone.