Runes

Runes (ルーン文字) are the letters in a set of related alphabets known as runic alphabets, which were used to write various Germanic languages before the adoption of the Latin alphabet. In the world of Toaru Majutsu no Index the alphabet is used in various magic spells and rituals, known as Rune magic (ルーン魔術), the most notable is that of Stiyl Magnus and his Rune cards.

Principles
According to the Index Librorum Prohibitorum the twenty-four characters are used to indicate mysteries and secrets (Rune means "secret") have been used as a magic language by Germanic tribes since the 2nd century and are found in the roots of Old English.

Rune card
Rune card or Runic card (ルーンカード) is a magical tool that has the runic language printed on them, primarily used by Stiyl Magnus, it is shown to perform various types of spells depending on the runes used and the numbers of cards used. When used however, the magician requires them to continuously provide mana for the cards to operate, for example: Stiyl leaves runes in the hall near Touma's room which would summon Innocentius when an intruder comes near. However, because of this, magicians can easily track the mana left by magicians.

There are currently 24 runes, and according to Stiyl he has analyzed all of them and has created new power using six character runes. It is unknown what these new six runes are at the moment.

Appearance
The content of the card consists of a magic array, formed by four circles encasing a pentagram with a rune mark in the middle of it. The outermost circle is colored yellow, the second outermost is darker yellow-colored perhaps orange (the first novel features this) where there are five crosses that jut out of the five points of the pentagram, the third is a thick black line, the final circle is color red. Here, the pentagram is lined black, with the insides colored white. The black rune(s) is inserted in the middle of the pentagram.

The four edges of the card have diagonal crosses that touches the edge of the outermost circle. Finally, just below the outermost circle is some small text.

The cards are also laminated, as so water could not damage with the printed material on the card.

Toaru Majutsu no Index
The rune card is used by Stiyl Magnus as a replacement for the print paper marked with runes he originally used, after failing spectacularly against Kamijou Touma, who washed the ink of the runes off the print paper with the emergency sprinkler system of his dormitory. Stiyl has been using the cards ever since.

The only other person shown so far in the series using Rune Cards is Acqua of the Back, who use the 'laguz' card that controls water to attack the Amakusa Church. This is just one of the many attacks that Acqua has shown.

Abilities
This is the list of runes used for a spell, most of these however are used by Stiyl Magnus and his rune cards. As stated the type of spell that is created from the cards are dependent on the runes printed on it, the power of the spell is also dependent on the number of cards used.

List of known Rune card spells

 * ᚲᚨ kaunan(torch) and ansuz(one of the Æsir) - Used to summon the Witch Hunting Pope, Innocentius. The more rune cards used the more powerful Innocentius becomes.
 * ᛟ opila(heritage, estate, possession) - Used to create Empty Space, magic spell that isolates chosen individuals within the vicinity where the cards were applied, here, the anime depicts the effects as if every activity cease, background noise disappear and everyone other than the chosen individuals disappear. According to Kanzaki Kaori, the spell merely diverts the attention of the people away from the area.
 * ᚲ kaunan(torch) - Produces a flame spell when used, or more precisely, it ignites things.
 * ᛇ Eihwaz(Yew-tree) - Undetermined, but seems to be used as a seal.
 * ᚨᚷ ansuz(one of the Æsir) and Gebo(gift) - Used to hide one's presence.
 * ᛈ Peorð - Creates an illusionary body for the user, allowing the user to escape.
 * ᛁ Isaz(ice) - Used as a restraint, making anyone who tries to move while the runes are applied unable to move.
 * ᛋ sowilo(Sun) - Disperse by-standers spell.
 * ᚨ ansuz(one of the Æsir) - Communication spell.
 * A rune that prevents magicians from refining magic power.
 * A rune card that essentially acts like a security camera.

Others

 * Laukaz - A combination of the runes appear on Freyja's womb when the child reveals herself to be the one in control of her mother. Laukaz the rune, means "leek" or Laguz meaning "water" or "lake". It is also hypothesized that the letter is a symbol to represent fertility, fitting as Freyja is the goddess of fertility.

Trivia

 * Only Stiyl has been shown to use the cards, though it is assumed that other magicians who uses runes can do so as well, especially from Necessarius itself.
 * In manga volume 3, a joke is played out where Stiyl adds a bladed border to the Rune cards, and uses them to bypass the Imagine Breaker by using them as darts.