Lightning Cross Prison: a small attached external space covering three square kilometers, with the attributes of death and lightning. It could suppress one hundred undead.
Because lightning could dispel baleful and evil forces, it had an extremely strong suppressive effect on powerful abomination undead.
After Gu Xi connected Lightning Cross Prison to the Mirror Dungeon, the relevant information about it appeared in his mind.
Of course, the Book of Life and Death in Gu Xi's hands contained even more detailed records.
This gave Gu Xi a certain understanding of the Lightning Cross Prison before him.
At the same time, with something to compare it against, Gu Xi also classified the Netherworld spaces attached outside the Mirror Dungeon.
In Gu Xi's view, all medium-sized spaces covering more than ten thousand square kilometers would be called Ghost Prisons, while those below ten thousand square kilometers would all be called prisons.
Classifying them by size was quite simple.
Gu Xi had no intention of classifying them by attributes or by the number of undead they could suppress.
As for anything larger, another tier would probably only be established once it exceeded a million square kilometers.
Gu Xi had not yet thought about how to classify those.
After all, a million square kilometers was an enormous area. Even the Mirror Dungeon currently controlled by Gu Xi had not reached that standard.
If Gu Xi truly wanted to seize such a vast Netherworld space, he would probably have to wait until much later.
There were no corresponding attachment relationships between the Netherworld spaces either.
After completing the conversion of Lightning Cross Prison, Gu Xi left five hundred Liches behind to guard it and simply put away the rest.
After handling matters here, Gu Xi flew back again.
When he returned near Poison Peach Mountain, Gu