Evil God's Whisper.
The Old World's total population was less than a hundred million. That was why.
Most Evil Gods needed believers to serve them, so they did not have to personally handle many minor matters.
They developed believers through Mad Invasion.
Even living in a human main city did not guarantee absolute safety.
The Evil God's whisper was everywhere. Perhaps one day, you bought a tabby kitten from a pet store... In reality, its mother had been affected by Shub-Niggurath during childbirth.
When you slept at night.
The little cat might leap onto your bed. Tentacles would grow from its body as it emitted a faint Evil God's whisper, allowing madness to slowly erode your soul.
People with stronger wills might not immediately transform. At first, they would suffer from mental decline, loss of appetite, and vomiting filthy substances.
Within three days at most, the individual's soul would be thoroughly contaminated, separate from the basic human body, and become an indescribable entity.
Perhaps one day, you felt sorry for a beggar by the roadside and stepped forward to give him two copper coins.
Gradually, you would discover that wherever you went, you would encounter this beggar.
You would also always feel as if he were saying something in your ear.
One day, the beggar would transform into an evil demon and go to worship Abhoth. You, meanwhile, would become a beggar and take his place as the "ferryman."
Crow Envoy—Chen Jingtong had been orphaned since childhood. Living alone in a dilapidated countryside house, he would find a crow landing on his parents' graves and cawing loudly whenever he went to pay his respects each day.
Slowly, the young Chen Jingtong became able to communicate with the crows. By the time he reached adulthood, he could control dozens of them.