Tower of Gungnir (グングニルの塔 Gunguniru no tō) is a Summoning Magic Spell.
Tower of Gungnir or also known as Grimoire The user stabs his palm with a blade and by using the blood, the user draws a magic circle on the floor that serves as an entry point for the tower. The tower holds vast amount of magic knowledge in a form of books, and thus categorized as a Lost Magic. If this magic falls to the wrong hands may lead to the destruction of the magic world. Many have searched the globe to learn this kind of magic, but none prevail.