Nix didn't kill the Beast King and let him mature, she can kill him whenever she wants. He was just a test subject for the abnormality she encountered, maybe she could find a lead once the Beast King matured. She believed whoever being behind this couldn't let the Beast King alone if he succeeded in absorbing completely the black light here. She just have to follow the seed planted beforehand in the Beast King and who knows she might get the jackpot.
Nix left the area shortly later. Of course in the guise of taking gift she put the powerful origin masters she encountered under her spell. Getting some useful tools in the human world she could use at any moment is a must.
She was glad she went out for this stroll.
°°°
A few days later.
Giant Beast Forest.
