I Fooled the Whole World with Just One Sentence

Sun Tzu, a rural boy who feels as frustrated as "Grandson" in reality, was reading "The Secret History of the Imperial Court" when he accidentally traveled to a mysterious parallel universe. As soon as he landed, he found himself in a mortal battlefield. With a confused look on his face, he subconsciously shouted "I am an immortal" and fooled everyone, thus starting a thrilling adventure. In this world, immortals, warriors and mortals coexist, and there are strange rules of war. When countries go to war, they must first determine the level at which they will participate in the war. Those with similar strengths will compete against each other, and people from other levels will serve as referees. Mortals can practice martial arts and become immortals. To cultivate immortals, spiritual roots are required, and to cultivate martial arts requires qualifications. Even if you don't have the qualifications, you can practice martial arts but the results are not good. In addition, there are anecdotes such as becoming immortals through literary skills. After death, people become ghosts and can practice rebirth. There are more monsters lurking in the world, and there seem to be mysterious forces behind everything. Although Sun Tzu has no spiritual qualifications, he relies on modern knowledge and "Sun Tzu's Art of War" to make clever plans on the battlefield and win the first round of battles amid dangers.