It works because blood is something personal that comes from you or another person who the spell is related to. It doesn't pose much danger as long as you sterilize the tool beforehand, and clean the cut afterwords. Also, if you do choose to use blood in something, don't think that you'll need a lot of it or hurt yourself; just a drop or two will suffice.
People do not seem to understand what blood magic is. And frankly, the constant repetition of it is rather annoying. Okay, what Supernatural episode did I miss that has everyone obsessed over blood?
Please use the search bar because I've posted on nearly every one of these "blood" related topics.
Blood magick is using a part of yourself in magick. It is giving one of the most intimate parts of yourself that you possibly can, the very fluid that keeps you alive. While semen is considered a man's strength and power, and menstral blood a woman's strength and power, we are still alive without these things. Blood magick is an itty bitty sacrifice. We are not killing anything, but we are offering a piece of ourselves, a piece of something very vital. Magick is all about the symbolism, and blood is symbolic of life and spirit, some may even say the soul.
Why would you attach yourself to a force you are using to push something away from you?
It would really all depend on what you were "offering" your blood to. You wouldn't just slap blood on something. Blood is precious. I use blood as a way to "seal" vows to show my dedication, and as a way to stain rune carvings because it is a way to feed the force of the runes themselves and bring them to life. Other than that, I rarely use my blood. I've used menstral blood far more often, not that you probably wanted to know that. ;p
The largest danger with blood magick is infection. It was back then and it is now. The other is having something like hemophilia (the disease that can cause you to die of blood loss from a paper cut). You need to be very careful and one drop is all that is needed. It's also good to take care of cleaning up after yourself well. Blood can carry contagious diseases and we don't test ourselves for those everyday.
The second danger is the spiritual one. Rule of thumb? Never offer your blood to a spirit unless it is a deity you know and trust. Would you give your blood to a random witch on the street you didn't know? I'm sure you are aware of how we use personal possessions in ritual. A strong spirit you are evoking (demon, angel, djinn, sidhe, whatever) that can manifest change in this world shouldn't have a symbolic source of your life given to them because you thought it would help get whatever you wanted. This is why people come here later on crying "help me, I'm being attacked by a demon". They aren't going to admit to being incredibly stupid. Honestly, it's hard coming back from that mistake. So just don't do it.
Its very serious magick... You can incorporate blood magick into nearly all spells to increase the potency incredibly. However, I heard something from somewhere and I thought it was rather good - "Are you willing to bleed for it?" - when you think about it blood is so important, it keeps us alive, its us really! it contains our DNA our personal signature, which is why it asks if your willing to loose some of that for your magickal workings. Another thing that you must keep in mind that blood is a very powerful binding agent, you use your blood in a spell you are bound to it until your blood dries up and is no more... so until you die you will be bound to that particular spell or working. I strongly suggest doing a little more research before incorporating it into your workings... If you have anymore specific questions Horsefire, please feel free to ask me in a PM! Blessed Be!
Thank you all who took the time to tell me more about this type of magic. I do believe that I have learned something and will think hard before using it to make sure that if I do choose to use it I will use it properly