Following the entry for Magic, Magecraft is the ability to reproduce what can be scientifically realized regardless of time and funds. The limits of Magecraft have changed with time, as science evolved and sorceries from before became technically possible through science. However, modern Magecraft remains far inferior from that of the past, so much that someone like Medea, who comes from the Age of Gods when Magecraft was much more powerful, would seem like a sorcerer to the eyes of a modern magus, even though what she can do is not really Magic.

Thaumaturgy

Thaumaturgy is the general term used to refer to the several modern schools of Magecraft such as Astrology, Kabbalah, Alchemy, and Shinsendou. Divergences can be found among different schools, but the fundamental basis is “to convert Magical Energy inside the user’s body to transform the external world”. The practitioner acts in accord with the system that each school operates under to execute a pre-built program. That “program” is a set of universal rules that interfere with nature once they are enforced. The power that enforces those rules is the magical energy of the magus and the command to do it is made through his circuits. The greater the interference, the greater will be the amount of magical energy consumed.

Being originally magic, Thaumaturgy draws upon a predetermined power from the Root. However, because that amount of power is fixed, the more people draw from it at the same time, the more Magecraft’s capacities become mundane. In short, the greater is the collective number of magi, the weaker their individual power. Each school engraves their system of Thaumaturgical Theory into the world and uses the rules of that system to operate their spells. The efficiency of a system depends on how disseminated it is, as in the more people believe or use it. It is not uncommon for a system to not work properly when used outside its place of origin. In that regard, the teachings and holy words of the Church is the Thaumaturgical Theory with greatest number of believers and effective area.

The main aim of the Magi’s academia is to turn the impossible possible. If something cannot be achieved with modern Thaumaturgy, the magi research and develop their arts just for the sake of changing that. Powerful sorceries like High Thaumaturgy and Greater Rituals are ultimately challenges in order to reach the goal called Magic. After a certain point of development, differences between power and even between Magic and Thaumaturgy start to lose their importance in practical terms. Battles between two great Magi will not be decided by their power, but by who possesses the system whose rules has the fewer tears. It is not the power behind them, but the concepts they work under.

The activation of magecraft from an established school requires following a strict set of protocol, one step of which is spellcasting. When compared to the application process of a document, the act of application, acceptance, review, and issuance, spellcasting is the application step of magecraft. It is mostly a convention when utilizing magecraft with a broad foundation, but it has potent self-suggestive powers for those who practice their own style of magecraft. As the Magic Circuits that shape magecraft already exist inside a magus' body, incantations are the "personal adage" that help the magi transform themselves, a method to efficiently activate and mobilize the Magic Circuits.

Mechanisms

Resistance, a power inherent of anyone with Magic Circuits, the capacity to resist spells which aim to control the target by the spiritual medium (those among the lines of sleep, paralysis and coercion). By circulating magical energy inside his Circuits, one can reject outside magical energy that tries to invade his/her self. Therefore, it is possible to disrupt a spell before it can complete itself. A very efficient form of defense, it makes it difficult to affect even lesser magi. Also, those who are not Magi but still possess Magic Circuits may unconsciously protect themselves like this. Because of it, most magi use spells capable of physical interference rather than just spiritual ones.

However, what is being rejected is the magical energy, spell itself is not nullified. A spell that has already been completed and is manifesting its effects cannot be cancelled like this. Caster, however, is an exception. She can disrupt even completed spells due to her absurd amount of magical energy and because the structure of modern Magecraft’s spells are far inferior to those of her time.

Breathing and Walking is a key concept in Magecraft and Martial Arts. Though mainly affects one’s physical fitness, it also plays a role in the strength of nature interference. The absorption of outer energy (breath of life) to connect your inner world to the outer world. The acts of inspiring, expiring and everything in between are part of a process that allows one to take in or release the gods. The Magi use incanted spells to cause a specific phenomenon to occur, but those whose breathing, movement, body and very existence can cause nature interference are beyond that.

Origin

Origin is the starting point that defines one's existence and directs one's actions throughout life. It is the driving force from the inside of the Root that managed to stream out of the Source and take material form. The form it can take at times is that of a human being, and all humans match their actions to be in harmony with the driving force that originated them from the moment they enter into the world. These actions are more along the lines of an inherent compulsion that could be called a person's instinct rather than a conscious decision. If a person becomes awakened to their Origin, it becomes nearly impossible to stray from their Origin if it's even possible in the first place. It becomes an impulsive behavior one would follow as though it were an absolute order. The Ryougi Family is able to awaken the Origin of newborns, and Souren Araya is capable of awakening one to their Origin after receiving consent from the person beforehand. Araya claims that death and Origins are related, and his various experiments on death are used to further his knowledge on them.

Under the system of Magecraft, Origins are used to describe precise details about a magus, while Elemental Affinity indicates one’s general alignment. Magi with an Origin that is strongly expressed outwardly are sometimes removed from the normal alignments and there are times that the origin itself becomes the alignment. Most of those magi exhibit their talents as extreme specialists, allowing them to potentially reach higher grounds than normal magi. Even those without an Elemental Affinity are sometimes still capable of casting spells simply by following their Origin. It's possible for them to overcome great obstacles such as a lack of Circuits or a lack of talent for Magecraft altogether. Shirou Emiya's origin is "Sword" and his alignment as a Magus is also "Sword". He is unable to use magic of the five great elements with precision because he doesn't have any of them as an alignment, but it does allow for the manifestation of "Unlimited Blade Works."