The main character hides his strength

Kim Seong-cheol, a legendary summoner known as the enemy of the world, faces a disaster threatening to bring about the end of the world. Though he confronts it alone, he cannot defeat the Demon King, whose spirit form is impervious to physical attacks. Realizing that he needs magical power to achieve his goal, Seong-cheol hides his identity and strength. He returns to the Summoning Palace, where he was first summoned to another world, and begins training as a novice wizard.