The so-called method of appearance referred to the conditions that had to be met for a special NPC to manifest before people.
For example, the condition for the Treasure Mermaid to appear was: a settlement.
As long as a civilized settlement appeared, the Treasure Mermaid would carve out a pool nearby to serve as the instance's entrance and exit.
Rabbit Town happened to meet that condition, so the pool connected to Silver Coral Island had appeared.
Previously, Angel had only known the Treasure Mermaid's manifestation conditions. Now, through further searching of the authority, he had learned the appearance conditions for the "Rainbow Sprite."
—A settlement and a rainbow.
Like the Treasure Mermaid, one of the prerequisites for the Rainbow Sprite's appearance was a settlement. Beyond that, a rainbow also had to streak across the sky above that settlement.
To put it more vividly: a rainbow had to appear over a town full of humans.
That was not difficult to encounter in reality, but it was somewhat hard to achieve in the current Dream Crystal Plain.
The main reason was that Rabbit Town was currently the only settlement in the Dream Crystal Plain, and Rabbit Town was located inside an underground cavern. Making a rainbow appear within an underground cavern was an extremely difficult matter.
Of course, they could create an artificial rainbow, but an artificial rainbow would not trigger the Rainbow Sprite.
According to the information he had found, the Rainbow Sprite's appearance was most likely closely tied to naturally formed rainbows.
In short, if they wanted the Rainbow Sprite to appear, they would inevitably have to build a settlement on the surface of the Dream Crystal Plain. Then, they could only leave it to the heavens.
The authority of Celestial Change had now slowly taken root in the Dream