Castle of Black Iron - Chapter 8: Mental Arithmetic by Abacus

Stranded in a world not his own, in a body not his own, Kaden finds himself stuck as a low rank marine in treacherous waters in the middle of an ocean where only the strongest can survive and a count down until a war that would shake the oceans and the very world itself erupts, where the kings of the sea will devour the chum. Gamer System. Insert.

The world was at the brink of collapse. Humanity’s desperate battle against the Harbingers, monstrous alien invaders from another world, had raged for years, leaving cities in ruin and hope at an all-time low.Amid the chaos, Noah Eclipse, an eighteen year old with no past and no purpose, struggled to survive each day.Noah being a first-generation talent, with a common, unremarkable ability that never stood a chance against the Harbingers' overwhelming might, had spent years labeled a loser, while fighting to keep his head above water in a world that seemed to have forgotten him.But as fate would have it, everything changed one day when he was fighting for his life and at the verge of dying.[Congratulations, you have awakened an SSS RANKED Talent : Void Summoning][Congratulations you have unlocked one item : Eclipse blade!!][Congratulations : You have unlocked a new skill; Void Blink]He was reborn, and for the first time, he was no longer weak nor helpless.With all the creatures and the power of the void in his palms, he would bring an end to the apocalypse!

In an era brimming with noise, where danger and opportunity coexist, the practice of martial arts, various folk customs, strange tales, taboos, imperial courts, and the world of martial artists abound. Among these are the grandmasters, magical duels, ghostly encounters, divinations, invoking the divine, ritual plays, esoteric Buddhism, and the pursuit of immortality.In this diverse and complex world, where the three teachings intermingle and all kinds of people abound, the sphere of mysticism is filled with folklores and bizarre stories.It's a tumultuous time, where danger and opportunity exist side by side.Striding with his saber, Li Yan is determined to dispel all evil and embrace a world free from any taboo!

He became a teacher at the best magic academy in the empire.
….For being mistaken for someone else.