How It Starts.

Normally, the realm tree ought to call its children both inward and outward to come and test their worth within the tower of heaven. The message was supposed to be short and succinct. The trial of heaven would then start 800 years later. 

But this time the realm tree didn't call its children to the trial of heaven. She did give them a message as usual. 

She said, "We have survived another Origin cycle. The realm tree blooms again. But this might be the last time. This is because the whole realm faces a trial greater than the trial of heaven. It faces a trial that will determine its fate." 

Mother High Heaven's voice rang in all their minds. From the lowest intelligent beast to the highest Supreme Origin gods. They heard her regardless of their location in the void universe. They all heard her voice clearly, as if she were speaking directly and close to them.