If an elf comes into contact with a monster, they become a dark elf.
That's common knowledge known by everyone, from regular elves to guardians like Luna. Since they'd turned that common knowledge into a taboo, not a single elf doubted whether it was false.
If an elf has sexual intercourse with a monster and receives ejaculation inside their vagina, they become a dark elf.
That was the common knowledge the elders knew. Elves who get captured and gang-raped by monsters like goblins and orcs usually end up receiving ejaculation inside, and as a result, they inevitably become dark elves.
If an elf has sexual intercourse with a monster 'in a dungeon' and 'receives ejaculation inside their vagina,' they become a dark elf.
This was information that only I knew, and nobody else. The source of this information was none other than Estu. She revealed that the location—the dungeon—was crucial to the conditions for dark elf corruption.
