```
Inside the secret chamber, spiritual light shimmered.
The dull yellow glow silently penetrated the walls, and the ash-gray earth instantly seemed to endure the scorch of thousands of degrees, shrinking and solidifying into something incredibly hard.
Wang Chen, who had just cast the Mudstone Technique, withdrew his palm.
The Great Achievement level Mudstone Technique could penetrate a two-foot-thick layer of earth, solidifying the stone to be harder than refined iron.
This was precisely why Wang Chen had focused on advancing this spell to the Great Achievement level before he began excavating the bunker.
What he was planning was not merely an underground shelter for refuge.
The bunker had to be capable of withstanding attacks from spells like the "Earth-Shattering Technique," as well as resisting the invasion and corrosion of the Earth's energy. Lower-tier Mudstone Techniques simply couldn't meet the design specifications.
