Modifier of Life and Death

When Lu Ci woke up, he saw a death countdown hanging above everyone's head. The green one is normal, the red one is dying. He looked in the mirror - the top of his head returned to zero for three seconds. But he didn't die. From then on, he can change other people's countdowns at the cost of his own life. Then he received a text message: "Six days left. You can't run away."