Upon discovering the existence of the Backyard in the late 20th century, The Original laid the foundation for what would become the study of magic. When he realized his error in creating the Universal Will, he warned the scientific community of an incoming catastrophe, but only a few—those who came to be known as the Apostles—listened. When his prediction came to pass in form of the Dawn of Revival, only his disciples were prepared to provide swift relief to mankind.
In order to restore human civilization, they they helped the world adapt to magic. Though the early stages of magic research were difficult, the Apostles continued to push forward, expanding human knowledge of magic very quickly. The results of that process were, presumably, published in the form of the Arcanum, but the original research that led to the book's creation remains in possession of the Apostles, nowadays known as the Conclave.
Little is known about the Arcanum, only that it contains information about 666 spells, yet six of them have been banned, so in actuality there are 660 castable spells. This set of spells are known by the term of Forbidden Magic (禁呪, Kinju?), and were deemed too dangerous to attempt, or about which too little is known. They involve incredible risk, or can cause horrible side-effects for the caster. Currently, only two of them are known:
- 5th Forbidden Magic Spell, Life-Eating Shadow (卑・泥獄墜法第５法「蝕精影陣」, Hi-Deigokutsuihō Daigo-hō "Shokusei Kagejin"?) or Pact of the Shadows which binds a Forbidden Beast to the caster's shadow, although using the shadow too much will erode the host's life force. The researcher who discovered the spell was so afraid of its effects he put a seal of protection on it that required anyone who cast it to give up their sight. It was used by Zato-ONE, who became a host to Eddie.
- 6th Forbidden Magic Spell, Angra (卑・泥獄墜法第６法「アングラ」, Hi-Deigokutsuihō Dairo-hō "Angura"?) or Covenant of the Condemned which, upon casting, enables the user to freely manipulate and control their hair by paying a steep, but unknown price. It was used by Millia Rage, but it is unclear if she took the curse freely or if it was forced upon her.
Otherwise, the current contents of the Arcanum are unknown. It can be assumed, however, that many of the playable cast's abilities are based upon the spells written here. Known spells or types of magic that could be written here include:
- Element generation - ...
- Seal - ...
- Bind (バインド, Baindo?) - This type of magic immobilizes a target in a given spot.
- Barrier - Magic of this type enables the caster to produce a magic shield around something for whatever purpose, generally used as a protective measure. The most powerful known spell of this type is Absolute Defense: Felion, which can only be cast by the Conclave or the Sanctus Populi.
- Float (フロート, Furōto?) - A spell that enables the caster to float in midair; it is not a difficult ability, but maintaining a state of floating through inertia and friction requires a lot of training and time to execute.
- Summoning - The act of calling forth objects or even living beings is possible, as demonstrated by May, Testament, and Faust.
- Spatial Deformation - One of the most powerful types of magic, which can only used by those who fully grasp the theoretical underpinnings of magic and have a gift for information manipulation. Faust's abilities are believed to be of this type.
- Soul Sinker - ...
- Teleportation - ...
- Telecommunication - ...
- Climate control - ...
- It is unlikely that the Art of Resurrection or the Saint Oratorio are registered in this book.
- The word arcanum is of Latin origin, and means "mystery or deep secret". It also is taken to mean "elixir or secret remedy" in English definitions of the word.
- [GGWorld - "The Original"]
- Guilty Gear Xrd -Sign- script § "Philosopher B"
- [GGWorld - "Apostle"]
- [GGWorld - "Arcanum"]
- [GGWorld - "Forbidden Magic"]
- [GGWorld - "Pact of the Shadows The 5th Forbidden Magic Spell, Life-Eating Shadow"]
- [GGWorld - "Angra"]
- [GGWorld - "Covenant of the Condemned"]
- Guilty Gear 2 -Overture- script § "The Alarm Always Rings Unexpectedly"
- Guilty Gear XX script § "Baiken Path 3"
- [GGWorld - "Float"]
- [GGWorld - "Spatial Deformation"]