When Wen Yan chose the profession he deemed the safest, "Natural Enemy," he felt sure his ending wouldn't be the same as those of other professions, where the average person met an untimely death.
That was until he encountered a Soul Devouring Beast that measured tens of kilometers in length. He then realized things might be just a tiny bit different from what he had thought.

"Soul Devouring Beast.
Trait One: Devouring.
Devouring souls.
Trait Two: Immune.
Immune to physical damage, immune to elemental damage, immune to environmental damage, immune to mental damage, immune to sustained damage, immune to toxin damage, immune to..."
"Sole trait, Invincible."

Chapter 410 - Chapter 173: Paper Money, Team Annihilation (5k)_2