The Death Element is the crown of Darkness. It was automatically claimed by Darkness for it needed something to start out with. This is the base element for the use of Necromancy.
Its polar opposite is Life and without Life there wouldnt be a Death, but without Death Life wouldn't exsist either. Death is the controller of many elements like the element of war, element of corpses, element of weapons, but is by far not the most powerful element.