The End of the World, Starting with F-Level Dark Powers

[How Steel is Made] Fantasy version rises the city from 0 "I'm just a rat crawling up in the gutter, but I will bite off your neck!" Zhao Mo said lightly. Alien beasts have besieged the city for thirty years, and humans have huddled in the base city to survive. Awakening is the only threshold to cross life and death! His parents spent all their money to help Zhao Mo awaken, but what he awakened was an F-level dark power that no one expected. When the dark threads turn into invisible fangs, silently eroding the core of the alien beast; when the muscles and bones tempered by flesh and blood are stronger than fine steel—— This young man who rose from the dust will eventually use darkness as his blade, open the way with his fists, step on the bones of alien beasts, and strive to reach the top of the apocalypse!