Black witches practices dark magic to gain more power. They cannot measure up to a certain coven of witches when it comes to raw power, so they result to dark arts.
The Devilry Sisters are the only coven of black witches. They are the strong and malicious but they still cannot measure up to the power of the elder witch. The elder witch is the only one that can annihilate them in a snap of her fingers.
Since their dark arts are no match for the Elder witch, they seek a power source that they can give them youth, and immense power. The phoenix is the symbol of eternal life and power. They believe that consuming the heart and soul of a phoenix can give them power that can defeat the Elder witch and have them rule the world.
Almost four centuries ago, they have managed get a whiff
