"So at the start, it's like a training pagoda?"
Ming Shu smiled and rubbed his head. "Yes."
Qi Yu choked. "…Then what happened to those people in the pagoda when their challengers won against them?"
"They died too. It is only fair that way. However, it didn't last for long."
Someone broke the rule.
When the people realized that the Apocalypse Pagoda was not controlled by anyone, they tried to gain power from the pagoda itself. They wanted to gain power that didn't belong to them.
This kind of training used to happen once every 100 years. Then, it changed to once every 1000 years. The intervals got longer and longer.
In the end, the Apocalypse Pagoda was disappointed with the people in this world so it shut down and was never activated again. It became a jail for villains of the different worlds.
As time went by, the people of the Thousand Mirror World forgot what was the real purpose of the Apocalypse Pagoda.