When we talk about spells which are related to death, they are always risky. They can actually lead to someone leaving the world. So these type of spells should be performed strictly under expert guidance. So for the people who have consulted an expert and know how to do should do it.
 
Death spells are mostly cast by using music. There are anonymous music which is available which actually hypnotizes the person and when the person has fully lost his senses, he has no control over his body and mind, all he is working with the instructions by someone then spell could be cast easily. It would be simple and then you can easily make the person rest in peace.
 
Casting a death spell is not someone good as it might give happiness for some time but then the curse of death of someone will follow you. Your inner conscience may feel bad about it, your life can become troublesome, so certain things like this can bother you. Thus casting a spell can make you go crazy. Maybe the person has rested in peace but your peace of mind will be badly affected. So be careful when you think of death spell for someone.