I have seen a few but they can be very hard to find. Death spells are very popular weapons in the war against Christians.
They are not a good idea IMHO.
Wouldn't it be better to cast spells that make Christians sick, perhaps leading to their eventual death, so they can see how their god doesn't come through for them in their hour of need? Let them call upon their god, cry out to him, and beg him for mercy. He won't answer, he won't save them, he will abandon them.
The point is that doing so allows for the truth to come out in the Christians life. They can clearly see that their god has abandoned them. It opens the chance to conversion to the truth.
