There is a term in forest ecology that sounds ordinary enough.
"Thinning."
Any given patch of forest has only so many natural resources to go around. To keep the forest healthy and encourage its trees to grow, experienced foresters periodically... cut some of them down.
Done selectively, this helps prevent the forest from deteriorating and gives the remaining trees enough room to grow.
And now...
"If we think of different 'Worlds' as 'Trees' of different sizes..."
"Then a 'Forest' only has so much room. As more and more 'Trees' grow larger and more lush, they inevitably begin to encroach on each other's living space."
"Some lose their 'Sunlight.' Others have their 'Water' stolen."
"Or their branches simply spread too far and crowd out their neighbors."
"Often, the surrounding 'Trees' can only keep growing once one or more 'Worlds' are destroyed. Like felled trees, they leave room for the others."
"This is a war with the future of an entire 'World' at stake. One side must be wiped out completely. There is no room for negotiation."
"The 'Thinning' War."
Ling Ke had left the Pure White Great Hall of the Theater of Domination and was now aboard the Astral Express, explaining what he had learned from the Imaginary Tree.
His listeners were a bewildered Sirin and... a very attentive Kali.
Yes, Kali.
As the "Winner," the sky-blue-skinned Herrscher of Blood had already received her reward from Ling Ke. It was the very thing she wanted most.
The chance to follow her "God."
But Sirin had obtained that same opportunity through sheer luck. Ling Ke felt he ought to be fair, so...
Sirin still hadn't earned the chance to resurrect anyone, but Ling Ke casually brought Kali's parents back to life. Just as he had done when rewarding Seele, he also created a new universe for them.
There was no Honkai on that universe's Earth, either. Nor did Kali's family live in the slums of India.
Just as she had wished, they had a simple, ordinary home.
She could return to her parents whenever she wanted. On those visits, she took on her old appearance as an ordinary little girl so she wouldn't frighten them.
At other times, though...
"Exalted God, if there is a World you wish to destroy, Kali will do everything in her power to assist you," she said respectfully.
The Earth she had known no longer interested her.
It was just an insignificant planet on a single "Branch." Following her "God" would give her access to an entire "Forest."
"Rushing into other 'Worlds' would be too dangerous."
Ling Ke was quite protective of his subordinates.
"So, Kali, if you want to help me, stay within the Imaginary Tree's domain. With your abilities, commanding those 'Spawn' to hunt down invaders should be right up your alley."
"And don't worry. The more you accomplish, the more the Imaginary Tree will reward you. It won't be stingy."
"Your existing Authority could even undergo a complete transformation."
Kali grew visibly excited.
Originally, Ling Ke had intended to give her the Cocoon of Finality outright and bind it completely to her. But something was about to happen, so he had put that plan on hold.
He had no intention of keeping her guessing about it.
"Kali, a 'Stargate' will soon open within the Solar System."
"The mess on the third planet, Earth, is no longer your concern. I'll teleport you somewhere else before it opens."
Kali stood no chance against whatever was coming through that Stargate.
"Exalted God..."
The girl asked respectfully, "This 'Stargate' you mentioned... what is it?"
"Uh..."
Ling Ke froze for a moment.
Right. I forgot to explain that part.
"I compared a 'World' to a 'Tree' just now. Remember?"
"Mm." Kali nodded.
"Then, following that idea, what would happen if two 'Trees' kept growing and got too close to each other?"
"Their branches would intertwine," she answered at once.
"Exactly." Ling Ke raised his right hand, holding up his index finger. "A 'Tree' represents a 'World.' Its 'branches' are individual 'Universes.'"
"The forward growth of a branch is 'Time.' Its forks are 'Possibilities.'"
"When branches from two different 'Sources' touch, that's a 'Universe Collision.' A 'Stargate' is the point where those branches meet."
"Through it, invaders from another 'World' can bring the 'laws' of their side into ours."
"And with the 'Blessing of their World' protecting them, we can't forcibly erase them through 'Rules,' even within the Imaginary Tree's domain."
"The elite agents we send to their side have the same protection."
"Under those conditions..." A slight smile curved Ling Ke's lips. "The invaders, and even the natives of the other World, can only be eliminated through conventional means."
"Your mission, Kali, is to find those invaders and eliminate them."
"But this particular incident is far beyond your current abilities. Don't try to force it."
Kali nodded respectfully. "I will follow all your instructions."
Meanwhile, standing nearby...
(⊙_⊙)
Sirin was still completely lost.
She really wasn't very good at thinking things through.
Fortunately, Ling Ke had no intention of giving her the same work as Kali. She could simply be his little maid, without a care in the world.
As for the last remaining Herrscher on Earth...
"The Herrscher of Thunder will remain under your command. How does that sound?"
"Well..."
A flicker of disdain crossed his little follower's face. Ling Ke caught it immediately.
On this "grand stage," where was she supposed to find the time to babysit that reckless, hardheaded colleague of hers?
I feel like I'd get more done on my own. But the Exalted God is offering out of kindness... Hmm~
In the end, she accepted.