Mysterious Monarch In The Mortal World

When the mysterious phone call appeared, Qin Feng was faced with a life and death situation: if he answered it, he could save people, but he would be controlled; if he rejected it, it seemed like he would be free, but someone would definitely die.
Faced with these mysterious calls, he turned into a nameless hero, a female teacher, a low-key security guard, and saved all of the people who deserved to die.
But why was it that the mysterious phone calls had been terrible?