How to Cultivate the Immortal Killer Demon

The social animal who installed the battery traveled through the world of cultivating immortals and found that it was different from what was written in the novel. People here call electrical appliances magic weapons. Electrical energy is called mana. If you happen to have skills and start with endless energy, wouldn't you be able to become an immortal directly? No, why are there really immortals in this world? What should you do when facing an immortal? Want to kill? Should he be killed? Can you not kill?