The barrier of worlds is what separates human world from other types such as the kingdom of god, the void ( from chapter 18 ), the spirit world,  the mystical world and the world of demons ( that I will introduce later on ).

     Still, the number of contractors on earth was extremely small compared to that of the descendants of older generations contractors. But because their thirst for power was too strong, the descendants of former contractors did not hesitate to begin a merciless hunt for humans blessed by the gods. 

     Those were slaughtered as a result of their capture and every drop of their blood was extracted to be mixed with the stones of the tower. The massacre lasted several decades until the total disappearance of all contractor. Despite that, the tower could not be finished, the humans had underestimated the power of gods and had thought that a simple tower would have been enough to break the barrier of the worlds, their hope collapsed when they realized that the tower will never lead them to their goal. 

The pain of the Gods was immense when they saw their contractors fall in the traps of their persecutors and die to the last, they could feel each pain and suffering due to the contract but could not act.

[the contractor can use the power of a god and be in contact with it but the god cannot act remotely, he can protect the human in person only if he is physically in his world ]

Seeing their heart, the gods understood that the descendants were too impure to receive their blessing. They then destroyed the tower which was called Tower of Babel and decided to no longer descend in the world of humans, the stones of the tower were scattered on the earth and the years passed.

     Centuries passed and the gods progressively forgot the past actions of humans. They were content of the new generation's behavior and had forgiven the corrupted hearts of their ancestors. They were appreciative of the present generations whose heart was not filled with jealousy and envy. 

      None the less, the gods had not forgotten that the heart of Men was easy to corrupt, so they decided to create a way to strengthen the world of humans and thus allowing them to receive some of their power without their hearts being compatible with theirs, that way every human would receive power and will not fall on the same path as their ancestors. 

      Thoth one of the gods of knowledge was then sent to earth in search of a solution. At the end of the 31st day he discovered that the stones used to build the tower could serve as a catalyzer. When he transferred his energy in it, that one was filtered and then redistributed in the nature. The filtered energy was then absorbed in the human world without disturbing the balance of the worlds. 

But the god had also found out that the more energy he transferred in the stone, the longer the filtration process, he understood that if he filled the capacity of the stone to its maximum, several centuries would pass before this one could be redistributed in the nature and that given its capacity, it would take hundreds for stones to make a real impact on earth.

But the god though it was the best solution if they wanted to interact with human as before, without them reverting to power hungry beast, they had to give them equal opportunities. They then set out in search of these stones, which they filled with energy before distributing them back. After several years all the stones had been filled, what was left was to wait. 

In December 2012 the first stone filled with divine energy was discovered it had liberated the energy it contained and caused a landslide. 

The gods had not foreseen that even with the filtering of their energy some humans would still not be able to take the change of their world and would perish due to that. 

Decades passed by and after the energy released stabilized, it the then began to transform humans, introducing the Era of Evolved.