Sheffield

Sheffield is a Void Famliliar, serving King Joseph of Gallia. Her power is the 'Mind of God' which allows her to use any magic artifact and can create almost any magical feat.

She was summoned from the same world as Joseph, originally from humans on the other side of the Sahara and is the daughter of a priest. According to her, the humans on the other side of the Sahara have technology beyond that of Helkeginia's, but that is just a pale imitation of elven technology (and nothing like the Earth technology Saito used).

She served Joseph out of a desire to be loved by him, but did not succeed. Eventually she killed both herself and Joseph after Joseph was defeated by Saito, using a Firestone to burn both of them into oblivion.

Sheffield is also the only person shown in the novels so far that can fuse Void magic and Firstborn magic, with the results being the Jormungandr golems and the Firestones which can destroy entire airship fleets in one blast that can be detonated using Void incantations.