With the Gods of the Star Sea working together, the Abyssal Demon God could gain no advantage in those two planes.
The Abyssal Demon God had no intention of fighting the Gods of the Star Sea in an all-out war. After testing the waters, they withdrew and continued to develop the Plane Graveyard world, or pick on weaker targets in the Star Sea.
"With organizational skills like that, what were you doing all this time?"
The two Origin Planes settled safely into place, and Medivh and the other Gods of Light breathed a sigh of relief.
They couldn't help complaining about the Gods of the Star Sea. The Star Alliance had been doing just fine, yet they'd insisted on stirring up trouble, squandering everyone's trust until the alliance fell apart.
So you were capable of sharing the spoils after all. What took you so long?
If they'd realized that during the Star Alliance era, there would never have been fertile ground for the Three Sources of Evil to emerge.
By now, the Star Alliance would probably have gained the upper hand in the Plane Graveyard and might even have begun exploring the Primal Abyss.
It took getting hurt to learn their lesson. Only now did they understand that they couldn't swallow everything for themselves.
There was no point saying any of this now. The two alliances had shared the spoils only because they were under pressure, not because they meant it.
There was no trust left between the various alliances. They could never return to the Star Alliance era, when everyone stood together against their common foes.
That was simply the nature of the Star Sea's many spirits. Unless their survival was threatened, they wouldn't unite.
The Necrotic Scourge's rampage through the Star Sea had been one such occasion. It