If the Great Tianze during the day is a place where Cultivators can adventure, then the Great Tianze at night is filled with all kinds of dangers.
Countless Fierce Beasts have the habit of lying dormant during the day and coming out to hunt at night.
If Mu Can and Wang Cai had not set up an Array around, they might have been attacked by Fierce Beasts even before falling asleep.
Although after reaching the Void Level of Cultivation, sleeping has become less meaningful, they still can't continue exploring at night and must find a somewhat safer place.
However, the Big Formation they established served not only to fend off those Fierce Beasts but also to conceal them so they could enter the Reincarnation Pearl.
The New World within the Reincarnation Pearl Fourth Layer no longer displayed the bustling scenes of its early days.