The entrances to the hidden tunnels were disguised within natural rock formations, and their internal structure was reinforced just enough to prevent collapse while maintaining a natural appearance.
Over time, these tunnels formed a dense, interconnected network.
One that only Han Yu knew.
Even if a portion of it were discovered, it would not reveal the whole. And to ensure that risk was minimized further, Han Yu embedded self-destructing formations within key points of the network. These formations were subtle, triggered only under specific conditions, and designed to collapse entire sections of tunnel.
To an outsider, such collapses would appear natural.
Another instance of the mine's inherent instability.
Nothing more.
With the infrastructure secured, Han Yu moved to the next phase of testing.
This time…
With real subjects.
He chose carefully.
