Taking Earth to Investiture of the Gods

Yu Yu Heaven, the laws are strict.Heavenly Court above, Netherworld below, dynasties are sects.Immortals appear, ghosts and gods roam.The people plant spirit grains, cultivators become soldiers; using demons as servants, and ghosts as slaves.The protagonist transmigrates into the fifteenth prince of the Great Qian Dynasty, awakens a system, and can exchange for Earth's technology and manifest historical figures."This is awesome!"What stunned him was that the exchange required a killing value.And war is the most effective killing, then the protagonist is trapped in the cycle of farming—arming—farming—arming and cannot get out.