Black magic.
For stories visit
https://themythologyproject.com/black-magic-in-the-mahabharata
http://utkarshspeak.blogspot.com/2014/06/black-magic-in-malayalam-mahabharat.html
http://utkarshspeak.blogspot.com/2014/06/black-magic-in-malayalam-mahabharat_25.html
http://utkarshspeak.blogspot.com/2014/06/black-magic-in-malayalam-mahabharat_27.html