Based on whatever is shown till now, they are trying to call Ma Kali who is uncontrollable. They are hoping she will come to them. She has returned in her Parvati form but can change her form if she is called. They are trying to call her by such creepy ways. It is the biggest misconception. Ma Kali doesn't kill innocent people. She kills Asuras, -ve elements. She punishes them for their wrong doings. So a small mistake from their side will result in their own destruction. Ma Kali protects her children. They believe she will protect them from any of their wrong doing. I guess they are trying to clear these wrong ideas many people have about Ma Kali. Which will be more clear by the end of this track.
Regarding controlling Ma kali, only Lord Shiv has that capacity.
Bhakti, pious worship is not harmful. But when someone goes out of their way to achive thing through wrong means, there may be initial gain but have to pay a big prize for it.