There are normally no more than four Elementals (Or Apostles). They are the Dark Elemental, Death Elemental, Life Elemental, and Light Elemental. Each elemental controls the Beings who mach their element.
Before Heldspar, each Elemental was in war with the other, due to being possessed by the first members of God Hand. Elementals are chosen by a gruesome process known by few (though it is known that it involves reverse exorcism on beings). When Elementals die, the person who killed it absorbs its energies giving them some resistance to Beings of that element.
Elementals look like legless humanoids with a muscular top section. They have long fingers which allows them to have more control over spells. In death, Elementals have the power to massively shift the elemental focus of the land. Killing them is a must to those who wish to beat Heldspar