Grand Magic

Grand Magic (大魔術(だいまじゅつ)) was a term used to refer to  a world distorting spells that occurs in Toaru Majutsu no Index like, for example, Angel Fall.

Background
The term grand magic was used to refer to Angel Fall alone, up until Tsuchimikado Motoharu's explanation to Kamijou Touma regarding the use of Feng shui by Kamijou Touya to arrange the souvenirs and charms in his home to create a magic array. Here, Motoharu states the danger of moving or touching the souvenirs as would create an entirely new magic array, therefore a new spell.

Motoharu lists examples, and all refer to them in as Grand Magic:
 * Earthshaker (極大地震(アースシェイカー))
 * Phantom Hound (異界反転(ファントムハウンド))
 * Cocytus Replica (永久凍土(コキュートスレプリカ))

Trivia

 * The 2nd Toaru Majutsu no Index Soundtrack for the second season of the anime adaptation has the Dai Majutsu as the 7th track. Although none of the spells referred above are mentioned above, it most likely refers to the Large-scale spell La Regina del Mare Adriatico.