After reading Lin Zeyu's "Void Soul Stealing Technique," the three of Lu Heng all wore strange expressions.
If you say it's useless, that's not true.
This method indeed resolves the issue of the Void Eye being immovable, but the implementation is somewhat... crude.
Moreover, there is no forced contract between Lin Zeyu and this Void Soul Stealing.
This is different from Clyde Saville's enslavement of the Void Soul Stealing; Clyde Saville has the Spirit Communicator class, granting him absolute control power over the Void Soul Stealing.
Even if the Void Soul Stealing wants to resist, it can't.
Lin Zeyu's relationship with the Void Soul Stealing is purely one of rearing; if the Void Soul Stealing wants to rebel, Lin Zeyu won't be able to do anything about it.
However, there is one reassuring point.
The Void Soul Stealing is indeed very attached to Shadow Crystal Cores; as long as you give it enough, it can be made to obey.
