Fixed ways of thinking can be lethal.
We always think of ghosts as tangible entities, terrifying but at least visible and touchable.
But Yang Jian fully understood after he entered the Ghost Coffin and merged his consciousness with the Ghost Domain, enveloping the entire Huanggang Village.
The ghosts here are just like his situation lying in the coffin.
They're not ghosts in form, but in concept.
As long as Huanggang Village exists, this ghost will never vanish and cannot be imprisoned.
That's why Feng Quan, after entering the coffin, could control the villagers, and why Yang Jian, after entering the Ghost Coffin, could abandon his physical form to become nearly a purely conscious existence.
In reality, they had only temporarily experienced the existence of this ghost after entering the coffin.
However, Feng Quan didn't think in this direction; he regarded the coffin as a special tool, one that could perfectly transform people into ghosts.
But he was wrong.