in my opinion, there is some magic that would harm someone, whether the caster or the person the magic is cast to. however, even though in the path of wicca their rede says "harm none", i think there might be an exception, such as if you are defending yourself or someone else from someone who wants to harm you or them. i'm not very experienced, feel free to correct me on that if i'm wrong. that's just what i believe. i do also agree that not all black magic practitioners are all bad, (i've met some who are kind when i talk to them) just the same as white magic practitioners aren't always kind and good. (i myself have had my moments where i didn't want to be kind because i wasn't having a good day). if you ask me i see them as two different moods of magic but also equal to each other. what i mean is that you can have a good day and you'd do more good and positive magic, and other days you are angry and would probably do magic that would be harmful. basically i see white and black magic as just classification of spells. the white is for all the positve and good spells and everything, and black is for all the negative and harmful things, like curses and spells that would do harm.