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In Sword Art OnlineEdit
In ALfheim OnlineEdit
Spells in ALfheim Online usually have an elemental attribute, with each race being the most efficient with a certain element and its accompanying magic. However, each race can utilize spells of other elements as well, but the race will be most proficient in the element that they have an affinity for and might not be able to cast high-level magic in an element that they do not have an affinity for.
A spell is activated by chanting a specific incantation. The incantation consists of several «Words of Power», words in a language that is similar to old Norse, but is likely just derived from it. Each of these words has a specific meaning, thus similar spells share certain Words of Power.
As the language used for incantation consists of sounds that are not present in the Japanese language (e.g. Þ (th), ö, æ, v etc.), such letters are approximated in the Japanese katakana system, when reciting the incantation. For example, Þ (th) may be approximated as "shi", "se" and other similar sounds, depending on how the word is supposed to be pronounced.
The affinity for elements of each race:
- Sylph - Wind
- Undine - Water
- Salamander - Fire
- Gnome - Earth
- Imp - Darkness
- Spriggan - Illusion
- Púca - Sound
- Cait Sith - Beast Taming
Types of Offensive SpellsEdit
- Direct Fire - Spells that shoot projectiles that fly in a straight line.
- Single Homing - Spells that create a single projectile that homes in on the target.
- Multi Homing - Spells that create multiple projectiles that home in on the target.
- Area Ballistic - Spells that create a single ballistic projectile that upon impact damages beings within the area of effect.
- Weapon Charge - Spells which can be stored in a weapon and later fired at a target.
List of SpellsEdit
- Fireball - Launches a ball of fire that deals fire damage. 
- Dispel - Dispels a single magical effect with a spherical burst of red light. 
- Fire-Ray - A spell which creates a vicious, fast moving line of fire projected away from the caster. 
- Wind Blades - A wide-area, wind-attribute magic that launches numerous green blades that spread out in a fan shape and attack the caster's target.
- Wind Needles - A wind attribute spell that launches numerous shining emerald needles.
- Concealment - A wind attribute spell that creates an invisible green membrane over the caster and close allies, hiding them from the sight of monsters and other players.
- Lightning Curtain Seal - A spell that sends sparks throughout the target's body, sealing their movement. 
- Fenrir - Charges a players weapon with a bolt of green penetrating lightning which can later be fired at a target. While charged, lightning appears to scintillate across the weapons surface. 
- Vacuum Blades - A long range homing type spell that creates four or five boomerang-like blades of green light. 
- Night Vision - A spell that allows the player to see in the dark. Can also be used on other players as well.
- Metamorphosis - A spell that turns the player into a random monster, based on their skills. The end result is usually a weak monster, so this spell is rarely used in combat.
- Smokescreen - A long range fascination spell that creates streams of jet black smoke, which covers the battlefield and obscures anything in it from view.
- Hypnosis - A spell which allows the caster to control a single NPC. When under the effects of this spell, the NPC will show visible light effects. 
- Sacrifice - A high-ranking self-destruct spell that deals a large amount of damage in a large radius, but kills the player in the process. The death penalty after using this spell is several times worse than that of a normal death.
- Peeping - A spell that summons and attaches a familiar on the target player, allowing the caster to steal a look from the target's perspective. A debuff icon appears on the target's view for a second when the spell is cast, but can easily be missed by most players.
- «Moonlight Mirror» - A high level spell which creates a two way mirror that allows communication between two players. The length of time it can be maintained depends on the time of day, with the longest period being at night and the shortest during the day.
- Heal - A low level spell that can be used to heal damage of an ally.
- Aqua Bind - A binding spell used to restrict the movements of multiple opponents.
- Ice Knives - A non-tracking offensive spell that creates and launches four sharp ice pillars at a single enemy.
- Ice Lens - A low level distance viewing spell which creates an ice lens that increases the distance a player can see. 
- Revive - Allows for the resurrection of a player from a Remain Light.
- Aqua Stream - An offensive spell that creates a penetrating laser like high pressure stream of water. 
- Ice Tornado - An offensive spell that surrounds a target with a tornado of damaging ice. 
- «Purified Surface» - A spell that creates a surface of water close to ten meters in diameter. The water surface provides players standing atop it with a healing effect along with fire and poison resistance..
- Earth Wall - a high level earth-attribute spell that creates an impenetrable wall in a designated area. The wall can only be destroyed with high level magic or if the caster dies.
- Melody of Confusion - A musical song that causes a single NPC to become confused. 
- Melody of Aggression - A musical song that causes a single NPC to randomly attack anything within its range. 
- Searcher - A penetration spell that can be used in any attribute and helps break through camouflage spells and detect hidden players. When the spell is cast, multiple creatures, like fire lizards or fish, spawn and spread out in the area randomly, nullifying camouflage spells if the creature comes into contact with the hidden player.
- Tracer - A tracking spell that summons a small magical creature that follows the target and reports the target's position to the caster. The creature summoned depends on the race of the caster. If the tracer is destroyed, the caster will be notified of its death.
- «Hollow Body» - A high ranking transparency spell, which requires mastery in both hiding magic and covert actions. Unlike concealment, this spell allows the caster to move while invisible.
- Retrieve Arrow - A low level bow user exclusive spell which allows the archer to attach a magic thread to an arrow which allows it to pull something that cannot be reached by hand, if the arrow successfully hits the target. The downside of this is that the thread distorts the trajectory of the arrow, lowering the arrows homing value to zero.
- Butterfly Shield - A high level shield that surrounds the target with a swarm of butterflies. This shield is continually active and decreases the casters MP by a large amount for each attack the shield defends against.
Any spell chant that is interrupted or mispronounced will result in the Spellword Fumble Effect. This effect results in a large explosion and black smoke which damages the caster. 
See also: Sacred Arts
Spells in «Underworld» are actually system commands that allow the user to manipulate the game system, although they are regarded as magic by the residents of Underworld (referred to as Sacred Arts by the residents). These commands require a certain level of System Control Authority (SC Authority) and are activated by saying the command in English. All known commands typically start with "System Call" followed by a set of instructions, typically the generation or modification of an "element" or object.
Subtle fingertip movements are necessary for Elemental Sacred Arts, and the maximum amount of elements generated in a Sacred Arts Ritual is five for each hand.
List of commandsEdit
- Lit Small Rod: Causes a small, holdable object to become lit.
- Transfer Human Unit Durability Right to Left: Transfers the "Life" of a human held by ones Right hand, to a human in ones Left hand.
- Generate umbra element. Adhere possession. Object ID, [OBJECT ID]. Discharge: Creates an "umbra"/dark element object, which locates the position of an object with the specified object id and moves towards the item.
- Generate thermal element. Form element, arrow shape. Fly straight. Discharge: Creates an arrow(s) of fire, that flies forward.
- Generate cryogenic element. Form element, bird shape. Counter thermal object, discharge: Creates a bird shaped object(s) made of ice, which is (are) meant to counter a thermal object.
- Inspect entire command list: Grants access to the user to read a list of available commands. 
- Generate luminous element. Burst element - A basic ritual that releases a luminous element to produce a blinding light.
- Generate cryogenic element. Form element, shield shape. Discharge - A ritual that generates large round ice shields, probably for the purpose of countering a thermal attack.
- Transfer human unit durability, self to left. - Transfer the caster's «Life» to the human touched by the caster's left hand.
- Generate aerial element. Burst element. - Generates and unleashes a wind element, forming an explosive gust of wind.
- Deep freeze! Integrator unit, ID [3 digit ID] (ディープ・フリーズ！インテグレータ・ユニット、アイディー [3 digit ID], Dīpu furīzu! Integurēta yunitto, aidī [3 digit ID]?) - a command used to freeze Integrity Knights for an indefinite period of time.
- Remove Core Protection (リムーブ・コア・プロテクション, Rimūbu Koa Purotekushon?) - Allows others to apply a Sacred Art on the caster's Fluctlight.
- Weather prediction - A command that allows the caster to predict the weather up to several days or even a week in advance. This is a command that requires a lot of preparation and the exact syntax of the command is unknown.
- Armament Full Control Art - A high-ranking command that allows the caster to unleash the hidden power of Divine Instrument-class weapons.
- Synthesis Ritual - A supervisor-level command that allows the manipulation of an Underworld resident's Fluctlight and is mainly used in the creation of Integrity Knights. This command can only be used on Fluctlights stored within the Light Cube Cluster, meaning that the ritual is ineffective against real humans. The ritual takes 3 days to be cast due to a large number of parameters that need to be set for the ritual and can only be used on targets within the caster's line of sight. The exact syntax of the command is unknown.
- Full recovery art - A command that restores the caster's Life to the maximum.
- Wound healing - A command that seals the target's wounds by using a luminous element. This ritual is only used to stop the decrease in Life caused by bleeding, but it does not restore lost Life.
Sacred Arts SyntaxEdit
Elemental Sacred ArtsEdit
Depending on the function of a command, a "Sacred Art" may take on a variety of formats. Below is a syntax for Elemental Sacred Arts
"Generate [element] element. [Instructions]. Discharge."
This example is one of the more common formats that a spell might take. Here, an object of an element is created, and is given an instruction. "Discharge" is recognized as the end of the command in this case. Instructions can be any number of things, such as giving an object a shape, (Form element, [shape] shape) or dictating its movement. (Fly straight. Counter [element] object. Adhere possession, [Location])
Using a generated element, one can continue to feed instructions to a Sacred Arts Ritual, until all available elements are destroyed, or resources depleted. One may even hold off on giving instructions for a long period of time, so long as the elements still exists, and carries enough resources to perform the ritual. This was demonstrated, when Kirito generated a Luminous Element for light, and later gave it the command, "Burst element".
Even though these commands seem to take on a simple appearance, some commands may span many paragraphs. This was shown, when the Dormitory Supervisor, Azurika, used a "luminous element" object to heal Eugeo's destroyed eye, with a command that likely held a number of complex instructions.
Additionally, there are 8 elements in existence): luminous (light), umbra (darkness), thermal (heat), cryogenic (ice) and aerial (wind), aqueous (water) as well as the existence of "metal" and "crystal" elements have been confirmed.
Elements can also be combined together for an even greater effect, as shown when Kirito generated both a metal and a crystal elements to create a mirror. Using more than 1 element for a Sacred Art can be done by using each hand to generate a different element and then combining the two elements by slapping one's hands.
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Volume 3 Chapter 4
- ↑ 2.0 2.1 2.2 2.3 Volume 3 Chapter 2
- ↑ 3.0 3.1 3.2 3.3 Volume 4 Chapter 8
- ↑ Volume 6 Chapter 11
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Volume 4 Chapter 5
- ↑ 6.0 6.1 Volume 7 Chapter 6
- ↑ 7.0 7.1 The Day After
- ↑ 8.0 8.1 Volume 7 Chapter 5
- ↑ Volume 8 Caliber Part 5
- ↑ 10.0 10.1 10.2 10.3 Volume 12 Chapter 8 Part 1
- ↑ 11.0 11.1 Volume 9 Chapter 1 Part 4
- ↑ 12.0 12.1 12.2 Volume 11 Chapter 6 Part 2
- ↑ Volume 11 Chapter 6 Part 3
- ↑ 14.0 14.1 14.2 Volume 12 Chapter 8 Part 2
- ↑ Volume 13 Chapter 10
- ↑ Volume 13, Chapter 11
- ↑ Volume 11 Chapter 6 Part 2