Successor of the Azure and the Eye of Azure: The Successor of Azure is the one who "inherits the Azure" and is able to use the "Eye of the Azure." The Successor can directly access the full power of the Azure. The Eye of the Azure allows them to locate/Observe the Master Unit. There’s no other way to find the Master Unit in the Boundary. The Successor probably has many more special traits to be revealed.
Boundary Interface Prime Field Device, Murakumo Units, and Kusanagi (Sword of Destruction): Prime Field Devices are artificial humans (probably made directly out of Seithr) designed to explore the Boundary. They were necessary because humans can’t survive in the Boundary. A Prime Field Device found the Azure. Upon reaching the Azure, it gained a soul and obtained the Eye of Azure. It became sentient and godlike; the humans ended up sealing it in the Boundary out of fear (it's not clear if this means that Device is still in there or if it's destroyed.) The next iteration of Prime Field Devices were designed to have suppressed soul and emotions so they could be controlled. These new Prime Field Devices were not meant just for exploration, these so-called "Murakumo Units" were modelled after the Izayoi and designed as weapons. If a Murakumo Unit was able to obtain the Eye of Azure, then it would be designated a Kusanagi. It would be the sole existence capable of destroying the Master Unit. (It's very, very murky at this point who created the Prime Field Devices and when. Relius and Ayatsuki were said to create to create something called the "First Boundary Interface Prime Field Device" or the Zeroth Prime Field Device, but there were clearly Prime Field Devices before then. The XBlaze and BloodEdge Universes have their own Prime Field Devices.)
Takamagahara: Humans created a copy of the Master Unit that is controlled by an AI. The AI is divided into three modules: TA, TB, and TC. Takamagahara is inferior to the Master Unit in every way. It can only create Phenomenon Interventions on certain major events. Takamagahara counts as an Observer.
Smelting: This term is frequently used without much explanation. Black Beasts, Grimoires, Nox Nyctores are created through "smelting." Noel is "smelted" into a Kusanagi. I think smelting is putting something into a Cauldron and then turning it into something else using the Azure. Relius describes smelting as making something Observe itself and then having it refine its existence. The purpose of smelting is to make something more perfect. Smelting seems to require a huge amount of souls, which seem to be turned into Seithr.
Magic: The use of mana to distort reality. A great power that is connected to the Azure. It was discovered by mankind a long time ago to fight things outside of logic. This power spends mana, spiritual powers which are found in nature and can be controlled by the user's willpower. Due to the rarity of people able to use mana, Magic is scarcely seen or talked about.
Sorcery: The use of Seithr to distort reality. Similar to magic, but powered by Seithr. Like magic, only a few people can manipulate Seithr.
Alchemy: The use of science and technology to make objects, bodies, or even souls, more perfect.
Ars Magus: The use of science to manipulate Seithr. Ars Magus is powered by Seithr and consumes Seithr in order to work. The mechanism for using ars is recorded in a Grimoire. A spell must be performed in order to activate the Grimoire. Ars Magus can be used by anyone with a Grimoire. This was invented by Nine during the Dark War.
* Note: BlazBlue fights and conflicts are all about using Mana via Magic, Seithr via Sorcery (and later Grimoires), or the Azure to literally distort reality to do what the user wants to do. *
Grimoire: Grimoires are the devices used to perform Ars Magus. The purpose of a Grimoire in Ars Magus is to convert Seithr into another form. They essentially allow anybody to use Sorcery. Grimoires aren't necessarily books, they often take different forms. Grimoires usually do a specific 'magical' task, like summon a fireball or transform items. These were invented by Nine during the Dark War.
Ars Armagus: A more powerful form of Ars Magus. Unlike with Ars Magus, only those with powerful souls can use Ars Armagus. This was invented by Nine during the Dark War.
Nox Nyctores Causality Weapons / Causality Weapons / Phenomenon Weapons (事象兵器アークエネミー Jishō Heiki Ākuenemī: Archenemy Phenomenon Weapons): The final application of Ars Armagus. 'Causality Weapons' refer to a set of ten weapons that were modelled after ancient devices. Only those with the highest proficiency in using Ars Armagus can wield them. Even then, there is a significant risk of mental burden on the user. The Nox Nyctores are powered by huge amounts of Seithr (souls) compressed into a ball, called the core. It is said that the Nox Nyctores are sentient and choose their masters. The cores of Nox Nyctores 2 through 8 were made out of parts of the Take-Mikazuchi's original core.
|A giant monster that was sealed in a satellite orbiting the planet. Fires a giant laser, but needs about 4 years to gather enough Seithr for a single shot. Take-Mikazuchi was completed by Seven, Eight, and Terumi against Nine's wishes.|
|2||Mucro Algesco: Yukianesa||Seven
|A Katana. The blade is formed from a special ice that never melts. It can crystallize the water in the air to use as weapons. Yukianesa amplifies emotions.|
|3||Arcus Diabolus: Bolverk||Three
|Guns that can hit targets at will in the desired location, regardless of walls. Bolverk pierces through space, detonating an Armagus-based blast wherever one aims it. Bolverk suppresses emotions.|
|4||Deus Machina: Nirvana||Celica
|A autonomous machine doll. May be meant for defensive purposes instead of offensive purposes.|
|5||Mucro Somnio: Musashi||Jubei||A sword that can cut through things that can't normally be cut.|
|6||Interfectum Malus: Okami||Hakumen||A nodachi that can nullify Ars Magus.|
|7||Arma Reboare: Muchorin||Trinity
|A long staff that can materialize matter. Muchorin causes memory loss.|
|8||Geminus Anguium: Ouroboros||Terumi||Chains with snake like blades at the end. The chains have infinite length. Ouroboros can directly damage the victim's mind.|
|A 55-inch nail that can be used as the core of Kushinada's Lynchpin. Rettenjo has the power to destroy the other Nox Nyctores.|
|10||Lus Sanctus: Murakumo||Nu||A massive sword that can destroy the Original Units because it is immune to Intervention. This Nox Nyctores was the only one created Post Dark War.|
Black Beast / God of Calamity:
A Black Beast is a giant, monstrous creature, usually described as having Eight Heads and innumerable tentacles. It releases and consumes vast amounts of Seithr. It can release miniature Black Beasts called Remnants. A Black Beast is a being 'outside of logic' and can not be damaged by normal means. Other beings 'outside of logic' (like the sorcery-created Valkenhayn) can damage it, but everyone else will need to use special means (some form of Magic or Sorcery). A Black Beast is formed when a Murakumo Unit unsuccessfully combines with the Azure (whereas a successful fusion would result in a Kusanagi), but there may be other methods.
Ragna and Nu fused into the Black Beast that was responsible for destroying half the world's population. This Black Beast was the cause of the Dark War, where the Six Heroes ultimately gathered and developed Ars Magus in order to defeat it. After Hakumen, the leader of the Six Heroes, slew the Black Beast, the Black Beast broke up into a vast amount of Seithr, poisoning the world.