There existed a high thorn wall that surrounded the palace, which was located at the heart of the capital of Heita, or the Underground Empire. It was the final defense against any invaders and was about 100 meters tall. Its magical properties allowed it to detect beforehand any intruders that would do its master harm, as well as stopping them from entering.

Its defensive capabilities were peerless, and anyone lower than level 8 wouldn’t be able to damage the wall regardless of what they did.

It might go differently if one used magic or an element, but pure physical strength and skills wouldn't be able to damage the wall. In a way, it could be considered an authority in its own right. The thorn wall's defense was absolute, and only after getting through that wall could the heroes even dream of challenging the Emperor.

"I didn't think there'd be one here too..."

"A thorn wall... I caught a glimpse of it before. It was at least 80 meters tall. Though it does seem smaller than the one in the capital."

"It wasn't here the last time I visited, which means it was created later. As I thought... There were rumors that the Empire was undertaking some secret project with even the high rank nobles none...