Profound Yin Jade is a type of spiritual object with intense yin energy, favored by cultivators who engage in ghost nurturing and corpse refinement.
Ghost pots and corpse coffins made from this material substantially aid the growth of ghosts and refined corpses.
Normally, no cultivator would allow their remains to be placed inside a Profound Yin Jade Coffin, as this easily leads to corpse transformation, turning them into a zombie, a type of yin creature.
However, if a cultivator does this, it indicates that they intended for their remains to transform into such a zombie in order to serve as the ultimate guardian of their tomb.
At this moment, Zhou Mingde was clearly suspecting that the tomb master had deliberately used this method to transform into a zombie to guard the tomb.
Shen Borong and Ruan Hongzhuang both agreed with this speculation.