My Clan Cultivation System: Only My Clan Can Cultivate

Reborn into a brutal realm of mages and heavy knights, Kael finds his new family—a wealthy but martially weak merchant clan—targeted by greedy nobles in a crumbling kingdom. ​But Kael holds a secret that will shatter the world's balance of power: The Clan Cultivation System. Will his family survive the dark world or will they become the monsters of the world themselves . — Description from novelcodex.org