Why Is There a BOSS in My Body?

Six years ago, the overlap of different universe dimensions occurred, the space barrier was broken, and a large amount of spiritual energy was poured into it, which caused huge changes in the creatures on the earth. Extinct creatures such as saber-toothed tigers, woolly mammoths, prehistoric giant crocodiles and even dinosaurs appeared one after another. What is worse is that the emergence of space barriers led to the invasion of extraterrestrial creatures. Human beings are affected by spiritual energy. Some people successfully evolve, while others are infected and become walking zombies. Shadow Barbie, Butcher, witch zombies, and fog zombies are rampant, and the entire earth has become an apocalyptic arena. The Little Rookie, who had been struggling in the apocalypse for six years, was reborn. He originally planned to rely on his foresight to work steadily and plunder resources step by step, but he didn't expect that there was a BOSS in the Little Rookie's body... "I've unlocked the health barrier and want an invincible rhythm?" The rookie looked confused.