So you ask, are there types of magic that are dangerous to practice?
Or what are things that make magic safe or dangerous?
Magic is a tool, just like knife. It is hand of the practitioner that heals or causes pain.
So, Necromancy, demonology, sex magic, angelology, shamanism, altered states, etc. etc.... There are people who approach any kind of magic carefully and with open eyes and mind and can do a lot of good for themselves. And then there are people who are seeking to cause harm using magic. And then there are people, who hurt themselves with magic.
Magic is like a catalyst. It strengthens what is within you. That can allow you to solve your internal issues. but used wrong it will increase issues into dangerous and even incontrollable situations. If you have mental issues within yourself and won't resolve them, magic can lead you into madhouse. This is rare, but it is not problem of magic. It is problem of the one who was practicing wrong and repeatedly did not learn from their mistakes.
I do vampirism. I have vampiric spirit around me. Since I stay in control and balance. it is safe. If I didn't keep my feet on the ground, it could become very dangerous. I also practice with a sword, weaving it in the air in semi dance. If I held it wrong, I could even kill myself. But I don't. I am careful, mindful, and I practice and learn. It has been over 10 years since I got my last scar from cutting myself with my own knife. Control and discipline is skill of immerse value.
You can do necromancy, it can be very fulfilling and enriching type of magic. On itself it is just that. Go for it, slowly, and watch for what mistakes you do and learn. Improve yourself. And one day you can be very powerful necromancer, without causing everyone around you to fear you.