Reigner modificates the world and takes the control of another one.
In this darkness world, Reigner could only rely on himself and his second reincarnation. There was also his foster mother, but she already provided enough information. This world was lacking in any energy and structure, because it was the world modification progress.
Reigner had to turn this darkness into his own world and then fight with others.
"There is a high chance the people from higher world also got pulled. This is going to be a wild battle, Reigner!"
"I know, but how do I change this world into my own one?"
"The best thing would be spreading your energy around."
Of course, if there was not even a clue one should go for the supernatural stuff! A magic had answer to everything and so Reigner swore as he squatted. His hand touched the darkness floor, then he began imbuing his power inside.
Within his mind, a new knowledge appeared.
It was knowledge regarding his world.