Summoning

Summoning (召喚) is a field of magic, which involves bringing forth supernatural energies and entities from another place, often bound to follow the commands of the summoner.

Principles
Summoning spells involve calling in a specific target from elsewhere, such as an entity dwelling in one of the phases like an angel, demon or spirit, or supernatural energies such as Telesma or other magical elements, to a specific location, often the summoning site. The summoned target is typically summoned for a specific purpose intended by the summoner, such as for a summoned entity to carry out the summoner's commands, for fuel to carry out certain spells, or to infuse power into individuals or objects.

Summoning cannot be freely carried out by anyone for any target at any time and any place. The summoner needs to calculate the necessary values (names, numbers, colors, circles, directions, dates, the required positions of the stars etc) and precisely set up their ceremony (with the appropriate magic circle(s), direction, time, location, etc) for their specific target. Magic circles used for summoning are often complex and intricate, given the large number of factors which need to be taken into account for the summoning process to succeed, with the setting up of the circle being comparable to writing a lengthy address to make sure the target is summoned. The methods for calculating a summoning ceremony can also be applied to trace the location of a summoning site. Certain summonings can cause 'interference' for other ceremonies in its vicinity.

With the magic circle or temple prepared and the right conditions met, the summoner gathers their willpower and pictures the summoning target in their mind, performing an appropriate incantation and any other necessary steps, in order to summon their desired target.

Summoning ceremonies may also include a separate protective circle, generally separate from the summoning circle, to protect the summoner. In cases without a protective circle, either the summoner or the summoned target will be inside the bounds of the magic circle, while the other one will be outside. The overall idea is to keep the summoner separate from the force they have summoned, so that latter will not bare its fangs against the former and do them harm.

Summoning ceremonies usually have a corresponding exorcism ceremony (追儺の儀式) which is necessary for banishing the summoned entity. Forcibly stopping a summoning is not the same as completing the exorcism, and in many cases, a summoned being will generally remain until the corresponding exorcism is performed, particularly if released outside of the summoning site in an autonomous state (though it takes a large amount of energy to maintain this state without some kind of vessel). Performing the exorcism often requires the same temple or ceremonial ground used in the summoning.

The magic sword, a symbolic weapon which guides magical power,  typically to protect the magician by driving out negative powers but also capable of diverting power in convenient directions, can be used to guide summoning ceremonies.

Background
The Golden Dawn incorporated summoning into its magical research and its members performed various summonings over the course of the cabal's existence, with founder Samuel Liddell MacGregor Mathers being a proficient summoner. They also secretly possessed Blythe Road's Treasure, the previous form of Imagine Breaker, which was intended as the ultimate exorcism tool for dealing with uncontrollable beings resulting from failed summonings.

Aleister Crowley performed numerous summonings, including a Telesma-level summoning during his induction into the Golden Dawn which used a Tarot arrangement based on the Qliphoth, and experiments involving his wife Rose. Two particularly notable summonings marked key turning points in his life and the history of the magic side; his summoning of Aiwass in 1904 and the summoning experiment in 1909 in which he encountered Coronzon, previously summoned by Mathers to drive him to ruin.

Index Arc
Aspects of summoning were part of the healing magic which Index guided Tsukuyomi Komoe in casting in order to heal her wounds.

Toaru Majutsu no Index SS: Agnese's Magic Side Work Experience
One of the incidents which Agnese Sanctis, Lucia and Angelene were tasked with settling shortly after their Necessarius training, was the summoning of HMS Hood as a ghost ship and its subsequent approach towards France. Their mission was complicated by the fact that summoning site, located in a shipping container in Calais's harbor, was a shared ceremonial ground rented out to various magicians, with five having used it for their own summoning spells in the past month and all apparently unaware of Hood's summoning. It was eventually revealed that the owner who rented out the ceremonial ground, Jack Prometeria, had devised the ceremony so that his clients would inadvertently summon the ship with the combination of their own summoning spells, and also that due to a flaw created by this set-up, the ship would disappear before reaching land.

World War III Arc
During World War III, following the rise of the Star of Bethlehem, Archangel Gabriel was summoned as part of Fiamma of the Right's Project Bethlehem, using a summoning method derived from the accidental instance of Angel Fall.

Kamisato Rescue Arc
Machina, a member of the Kamisato Faction, is described as an Elemental Spirits Internal Summoner and known to use a Salamander. Toyama Luca and Karasuma Fran's improvised spell to rescue Kamisato Kakeru from the 'new world' included aspects of summoning.

Aleister Crowley Arc
During the events on December 11th, several of the summoning ceremonies in Aleister Crowley's past were shown or referenced during the ascent through the Windowless Building. In the present, Aleister made use of a shadowy magic sword, of the kind capable of guiding magical power and used for summoning, first for bringing forth the Karma chains and later for summoning Aiwass as part of his ceremony to destroy the phases. Aleister's approach to fighting the Magic Gods, drawing out destructive power from the gods themselves to defeat them while remaining human, was noted to be the way a summoner thought.

Coronzon Arc
During the Attack on the Queen Britannia, Aleister made use of three rubies, symbolizing the blood sacrifices used to summon Coronzon, in conjunction with the ship's temple to intentionally enact a failed exorcism in attempt to tear the demon apart (with an analogy being made comparing a summoning circle to a sci-fi warp gate, with the power to forcibly send it back between the phases being used to slice the demon apart being compared to throwing someone into a malfunctioning fate and entering coordinate with a staticky signal), though Coronzon endured due to her physical vessel.