Question- what is the meaning of this? Can you confirm about this thirteen million crazy number, what does it represent? Is this crazy mordret’s work?

[Ascended! Prepare for your Third Trial!]

Its words echoed in the void.

[Thirteen million, seven hundred thousand, and seventy seven brave ones... welcome to the Nightmare!]

Sunny's eyes widened.

'...What?'

[End of volume six: All the Devils Are Here]

I like spoilers- so don’t hold back.