One hundred years

From the weakest to the strongest, they all began to work when they heard Roku's words. Although he did not kill anyone during this first battle, everybody knew the outcome would have been much worse had not the Astral Fiend kept the Divine Champion at bay.

Even the other Gods Slayers considered the Astral Fiend as their de facto leader inside Gods' Tomb. 

The Magic Tower that would work as the Magi Divine Slayer Force's headquarters needed to be strong enough to resist the Divinity Faith Army's full force, and nothing beneath Pseudo Rank 7 could achieve that might.

Constructing such a majestic and powerful tower in seven months would not be easy, but everyone present had the power to move mountains and split oceans, so it was not an impossible task.

The Scientia Kingdom's Magi were extremely experienced Magic Tower builders. All knew they despised schemes and hidden tricks, so they took control of the Pseudo Rank 7 Magic Tower construction.