Black datura is a mysterious plant in both Eastern and Western cultures. They always bloom near the execution site, like calm bystanders, recording every moment of life's passing.
There is an elf living in every black mandala flower, and they can help you realize your wishes. However, they also have a condition in exchange, which is human blood. Just use your own blood to water the enchanting black mandala flower, and the elves in the flower will help you realize your wishes. They can only water it with blood, because they love this passionate and fatal feeling. (If you are interested in the information on Baidu, you can check it yourself.)