What are the effects of magic, and can it be used for killing?

Yes, sorcery can kill, and whoever kills another with sorcery is usually killed in retaliation (qisas). If the sorcery is something that usually kills, then qisas is obligatory, just as if one killed with a knife. Otherwise, there is blood money (diyah) without qisas. The majority of jurists have held that killing by sorcery can be intentional and warrants qisas, and this is established by evidence or confession. The Shafi'is are of the view that if a sorcerer intentionally kills with his sorcery, then qisas is applied if it is proven by his confession or by the testimony of two just witnesses that the type of sorcery usually kills.