"If cultivators from the living world wish to become ghost cultivators, they must completely extinguish their physical bodies that remain in the yang realm before they can enter the yin world."
"Correspondingly, if a ghost cultivator from the yin world enters the living world, they will trigger a Heavenly Tribulation due to the lack of yang energy, and the higher their cultivation level, the stronger the tribulation."
"The so-called 'yang energy' refers to one's lifespan. Thus, we ghost cultivators who have come to the living world through the Yellow Springs Path must use the Art of Rebirth in the Underworld to find a body that still has an unspent lifespan to possess, to avoid the Heavenly Tribulation."
Elder Ming explained in detail.
