Black spark

Dai Lin became a surgeon at a strange hospital.
Here, they don't treat diseases but various horrific and mysterious curses! Divided into the Resentful Spirit Department, Malicious Ghost Department, Evil Ghost Department, Fierce Spirit Department, and the enigmatic Demons Department...
The eerie hospital, however, had some bewildering rules:
First, believe that the hospital is called Hospital 444, not 666 Hospital.
Second, between midnight and four in the morning, doctors and nurses must never enter the outpatient area.
Third, if you experience a severe headache and notice an inverted cross on your forehead, immediately seek treatment at the hospital's Demons Department.
Fourth, all doctors in the hospital wear white masks. If you see a doctor with a red mask, ignore them and make sure they do not realize you can see them.
Fifth...
And Dai Lin obtained a magical artifact, a pair of the Devil's Eye —the left eye could detect, sense, and attack, while the right eye could imprison, seal, and even devour and absorb.
And the source of all the terror in this hospital was the director who had never been seen by anyone...

Chapter 20: Dai Lin's Return