Ghost Nursing (1982)

Original title: 養鬼

Jackie is a young woman determines to reverse her bad luck. She consults the God of Gold, who advises her to "nurse a ghost". She is given a small figure to worship, and the worship includes dripping three drops of her own blood every three days. At first, all goes well and she falls in love. But this new happiness causes Jackie to forget to worship the figure, and the spirit doesn't like it. With good intentions, her new boyfriend, Raymond, discovers Jackie's strange predicament and attempts an exorcism which goes horribly wrong. The spirit takes over Raymond, who starts doing nasty things.