Void

Void Magic is a lost magical element branch which is very powerful. It is based on the fifth of the Japanese elements namely "Kyu" (Void) but it is renamed as "Kyomu" in the anime.

Void magic, as implied in the series, is an element which does not focus on elemental magic (i.e. Fire, Water, Earth and Air); Louise has access to offensive spells like Explosion and Dispel, but other non-combat spells include World's Gate, a magic opening portals between Saito and Louise's worlds, and memory-wiping spells have been seen used by other Void Mages.

Void, however, despite its terrible impact, it is actually a useful element as it is the only element to match and be able to clash against Earth's weaponry.

Since it is very rare, there have been only four Void users and familiars after Brimir has passed on. These users and familiars are: After Joseph's death, Tabitha's twin sister became the Void Successor of Gallia as the power of Void went to her.
 * King Joseph de Gallia, the current king of Gallia (before being dethroned in Volume15); His familiar is Sheffield, the Myozthirirn, or the Mind of God.
 * Louise Francoise de La Blanc de Valliere, also known as Louise the Zero, a Noble and second-in-line for Tristain's throne (Henrietta's proclaimed sister); Her familiar and most loyal protector (not to mention her most important person) is Saito de Chevalier Hiraga, the Gandalfr, or the Left Hand of God.
 * The Pope of Romalia, Vittorio; In the light novels, it has been confirmed that Julio Caesar is his familiar, the Windalfr, or the Right Hand of God . However, none of this was explored in the anime: Julio was shown without a master, the Windalfr was never mentioned, and the Pope never actually appeared.
 * The last one is confirmed to be Tiffania. Also, she has knowledge of the Void magic, its users and their familiars. She had once accessed Jospeh's music box, which she plays as a song in Princess no Rondo. As she is a half-elf and also Albion royalty (Henrietta's first cousin; Tiffania's father, the Archduke of Albion, is Henrietta's father's younger brother). She does not have a familiar, with her about to summon one before being abducted by the elves in Vol19.

Trivia
 * Sheffield's magical creatures seem to have a same rune that glows like hers. Her power as the Mind of God allow her to use any magical artifact, and gives her insight into magic theory.
 * A Gandalfr has the powers to successfully use any material designed and used for weaponry.
 * A Windalfr has the powers to communicate with and command animals.
 * The Heart of God ( リーヴスラシル) has the name meaning 'Life' in Ancient Helkeginian language. This familiar is technically a vessel for magical power used by Myozthirirn to fill up with magical power while Gandalfr guards the ritual. Then Windalfr will transport the vessel to where the enemy is and release the spell, resulting in the genocide of a entire race. This was done repeatedly 6,000 years ago when Brimir was forced to do so to prevent the Human race on Helkeginia from being erased . In Volume 7 Chapter 11, and also Volume 19 Chapter 7, Brimir revealed he was so guilt ridden over what he had to do to his 4th familiar he cannot bring himself to even speak this familiar's name.