He says the ritual will "help her out" and bring her luck in Italy.Juju has been practised in West Africa for centuries, and it would be hard to find anyone in Edo who is prepared to say they don't fear it.
Dr Stanley commands Vivian to undress and wash in the hut outside the shrine, and when she emerges he blows chalk dust over her body and smears clay over her forehead, marking her out so the spirits can identify the soul that is being offered to them.
Then he asks her to kneel before him to swear the oath. The ritual over, Dr Stanley lifts Vivian to her feet.
"I didn't know it would turn out to be like this." She now sleeps with about 10 men a day, seven days a week, for €20 (£17.50) a time.
She will work even if she feels ill, even if she has her period, even though she has been badly beaten in the past.
"If she breaks the promise she makes at my shrine, we need blood from her," Dr Stanley tells me on the morning of Vivian's ritual. I can throw any type of sickness to a person, whether cancer or stroke." He boasts that "uncountable" trafficked women have sworn oaths at his shrine.