Some magic is primal and basic and instinctual and very powerful, but most has some other element which means that people have managed to make it more effective through technique, but the nearest anyone gets to pure straight up undiluted magic is wishing. The wish is just what it seems, a wish, but of course there are ways to wish things onto your enemy such as the best way: that is the way that gives you the most powerful effect. It is easy to think of wishing as not powerful and not quite normal magic, and in many ways it isn't normal magic: but the power of wishing has long been recognised. There exists and still much used an evil eye emblem which exists solely to protect someone from the evil eye: the evil eye is a type of wish, and described at its most rudimentary form it is just a person looking at a person with hate. This of course brings me to an important part of wishing bad things on your enemies and that is you need to want it to happen and not just will it, but hate them enough for it to happen.