Nature, the sun, moonlight, death—they've all occurred naturally, so adding darkness isn't too much, right?
Not at all.
Each of the four Goddesses has a presence, so it would indeed be unfair if the Dark Goddess did not!
Anastasia, lacking a physical body, still felt the hair on her body stand on end as she said in disbelief, "Lord Wayne, does the Goddess have any instructions for me, and how should I assist you with the mission?"
"Just obey and do as you're told."
Wayne's skeletal head emitted white light as he finished speaking, and the ground at his feet began to swell with mounds of rotting mud and water.
The figure in Yellow Clothes slowly stood up, its pale, featureless face beneath the hood only showing twisted layers of proliferating tissue.
The Yellow Clothes extended tentacles, rolling towards Anastasia.
Anastasia retreated like lightning, on guard, "Lord Wayne, this is one of the Ancient God's Kin. What exactly is your identity?"