A Tripartite Hegemonic Balance!
The first group of survivors that came out of the inheritance ground was not Atlantian soldiers, they were mutated beasts.
As a veteran race that already had a mountain of book compilations on inheritance grounds, the Atlantian army already scripted the best reactions that soldiers were to exhibit in different situations.
The reason for their not coming out first was not complicated, it was simply because coming out first would draw the ire of the enemies.
Not all the mutated beasts that came for the inheritance ground after being attracted by their unrelenting desire were able to access inside it.
Some came after the entrance to the inheritance ground was already closed, others simply couldn't put up a good enough fight when the battle to enter the inheritance ground started, the scenarios were too numerous to count.