It is possible to kill someone with magick by ritualistically designating them as a human sacrifice to a given deity. Death curses usually take years to kill their target, and of course, this method kills slow. The victim is gradually devoured and killed.
I have not attempted this method, and probably never will. I am not a homicidal or sadistic person by nature, and I have never killed a human being through magick. Nonetheless, this technique has been tried on me without success, because I knew that some day, somebody would try it on me.
I have designated my death as an offering to a given spirit, such that when I die, no matter how or when, my physical life is sacrificed to that spirit. I did this partially because I planned on killing myself, and partially because I wanted it to be impossible for someone else to sacrifice me. The fact that I have considered both possibilities should tell you a lot about the life that I’ve lived.
This technique of magickal murder by sacrificial designation is growing in popularity, which makes it less and less reliable. It is possible that the person whom the magickian wants to designate as a sacrifice has already been designated, by another practitioner, as a sacrifice to a different divinity. Needless to say, this could lead to failure, and presumably, to offending two different gods.
Offerings do not need to be given in a ritual setting. Therefore, human sacrifice does not need to be committed during a rite, and therefore does not have to be murder. A person killed in self-defense or war can be designated as a human sacrifice even after they die. The Norse were known to hurl a spear over a group of enemy forces and proclaim them all human sacrifices to Odin in anticipation of their slaughter in battle.
As the spirit planes are not bound by linear time, someone killed long ago can be retroactively designated as a sacrifice.
We need not ask whether or not it is right to commit human sacrifice. Instead, we need ask whether or not a given person should be killed. In a self-defense situation, the answer to this question can be yes. My policy on human sacrifice is summarized by the idiom, “When life gives you lemons, make lemonade.”