The Nature of Magic is assumed to be a book in the world of Sanctuary, possibly written by Vischar Orous or Jered Cain. It's not necessarily a real book however, but it's found in the Diablo I Manual, and is written
Contents
Introduction
Magic is an extremely powerful force, the manipulation of which is carefully studied, frequently learned, but it is never fully mastered. Enchantments exude an aura that can be sensed by many, but years of training are required to properly exploit the Mana that pervades our world. Some scholars use natural manifestations to explain the workings of the universe. In a common archetype, the physical world is likened to the sky while the ethereal realm of magic is set as the ocean. If we follow this line of thought, spells are much like the turbulence that occurs where the two interact with each other. During the Sin War, Demon and Angel alike wrought powerful magicks that threatened to tear the fabric of reality apart. The physical and magical realms began to blur and merge, which, in our archetype, would be the equivalent of a fierce hurricane. The Forces of Order sought to preserve our reality by limiting the power of mortal man. As a consequence, only the strongest wills can harness more than the most basic of magical effects. Even then, much energy is lost in the transition of power between the two Realms. As a practitioner of the arcane arts grows more knowledgeable he is able to create these effects with greater efficiency, resulting in spells that are more potent, have more endurance and drain less Mana in their casting.
Firebolt
The true essence of Fire lies at the edge of Energy and Matter. It is, therefore, a fairly simple matter to shape Mana into a magical flame. Controlling a bolt of this fire as it flies towards its target is another matter entirely. As experience and knowledge with this spell grows, both the intensity of the flame and the speed of the bolt can be increased with the caster feeling less exertion.
Inferno
Inferno sacrifices the mobility of a Firebolt for pure damaging power. Rather than attempting to control the path and cohesiveness of a single bolt, the caster conjures forth an individual, focused stream of flame. Although it dissipates beyond more than a few paces, with a greater understanding of the forces at work the stream of fire can not only be extended a significant amount, but also can be maintained for a few moments more. The heat of an Inferno is more intense than that of a Firebolt as more Mana is being converted into essential energy.
Wall of Fire
Magical fire feeds upon no earthly source, being fueled instead by the mystic energies known as Mana. While the heat of conjured flames may cause normal matter to combust and burn on its own, the flames themselves will burn as long they have Mana to draw upon. By carefully controlling the flow of Mana to a magical fire, its life-span can be extended well beyond that of a Firebolt or an Inferno. The Horadrim were skilled enough to create torches that burn with an eternal flame, but those abilities have been long lost. With this spell, the caster creates a wall of eldritch flame that will burn until the Mana in that area has been exhausted. As knowledge of this spell increases, the rate at which Mana must be consumed can be better controlled and the Wall of Fire can be made to burn longer.
Charged Bolt
The true essence of Electromagnetism exists on the threshold of the Ethereal and the Physical Realms. While it is very efficient to transform Mana into electrical energy, it is extremely difficult to control. This spell calls into being multiple pockets of lightning which seem to have a will of their own. The caster is able to shield himself from the effects of these charges, but any creature – friend or foe – may be struck. Greater understanding of this spell allows more of these Charged Bolts to be formed, and their existence will be maintained for a longer period of time. The physical toll on the caster, however, increases as well, requiring more Mana to be spent.
Lightning
The caster of this spell seeks to control the discharge of electrical energy by focusing it into a single stream of Lightning. The effects of channeling this powerful force of nature onto an unprotected creature are awesome indeed. With experience, these bolts of lightning may be maintained for a longer period of time while requiring less Mana to be used.
Flash
The Flash spell was created to fight the servants of Baal, whose minions prefer to surround their enemies and attack from all sides simultaneously. To properly form most incantations, the caster must be able to concentrate long enough to complete the necessary invocations and gestures. With this spell, the caster draws in as much Mana as possible as quickly as possible from the surrounding area and concentrates it into a single point within his own body. This Mana is then released in a single burst of raw energy that dissipates very rapidly – and very violently. While this spell is usable only in close combat, it is extremely potent and will strike creatures on all sides of the caster.
Holy Bolt
While the Horadrim were the greatest mortal spell casters ever known, not all of the followers of the Light were as proficient in magic as they were. During the quest to bind Mephisto, common soldiers were hard pressed to combat the seemingly endless tides of the undead that guarded the First Brother. During this time, Cathan, a devout priest who was also a fierce warrior, found that by invoking the powers of the High Heavens and then infusing them with the essence of Fire, a bolt of great speed and intensity could be created and used by those otherwise untrained in the use of magic. This Holy Bolt harms only the undead, making it far safer to use while on a chaotic battlefield.
Healing
The art of self healing is an invaluable ability, and it is for this reason that this spell has been preserved throughout the ages. When cast, Mana courses through the body, instantly knitting broken bone, replacing torn tissue and reducing the effects of shock and fatigue. With time, this spell can be developed to the point that it can instantly restore even those on the brink of death. The ability to heal others is much rarer, and those that can do so are greatly respected.
Resurrect
During the assault upon Mephisto’s Fortress of Bone, the army led by the Horadrim was nearly overwhelmed by the legions of the damned. As soon as one of the crusaders was slain in combat, his body would rise again as an undead warrior to fight against his former companions. On the eve of what was to be the final attack upon the Fortress, a mysterious figure in white appeared before the Council of the Horadrim. This apparition revealed to them the secret of piercing the barrier between Life and Death. By Resurrecting the slain soldiers, they could be saved from eternal corruption. Those present at the Council swore an oath never to use this ability once the battle was over, but somehow the secret escaped. This spell has the power to bring a dead soul back to the physical world, but it must be performed at the site of the person’s death.
Identify
Any object imbued with magic exhibits an aura that is easily noticed. To determine the exact nature of this enchantment, however, requires intense study and an extensive knowledge of arcane materials and symbols. While none have mastered the ability to memorize a spell of this magnitude, the Vizjerei have developed a means for the untrained to discover the secrets of an ensorcelled object by using a rare crystal that is extremely sensitive to magical auras. This sensitivity makes it very fragile, however and the crystal will shatter if it is brought too close to an enchanted item. The very act of Identifying such an object also destroys the crystal. Scrolls and staves have been crafted that can be used to Identify magical auras. By using special inks and dyes that contain tiny grains of these crystals, the stability of the crystal is maintained until it is used to examine the enchanted object.
Town Portal
The Horadrim constructed numerous magical gateways between the mighty fortresses so that they could quickly concentrate their defenses against any incursion by the Demons. With but a thought, the Crusaders of the Light could transport themselves to predetermined destinations many leagues apart. Although the secret of creating these gateways has been long lost, it is still possible to use the pathways that are already in place. A Portal opened by means of this spell will always take the caster to the location of the nearest gate and remain open long enough to bring the caster back to his point of origin. The Church of Tristram is built upon the remains of a Horadrim monastery, and it is quite probable that a gateway lies nearby.
Telekinesis
This versatile spell is derived from a training exercise that was used by the Horadrim. Once they reached a certain point in their training, acolytes were bound and locked in a cell, with the key to the door lying on the floor in front of them. The student had to unlock and open the door without being able to physically move. Through intense concentration and fine control, the acolyte could manipulate the key as if it was held by an invisible hand. Those that were able to open the cell door were allowed to proceed to the next level of training. There is some speculation as to the fate of those unfortunates that lacked the magical prowess to escape. Today, this spell serves as a reminder that what was once a simple mental exercise for the Horadrim is now a difficult spell known by few sorcerers. Telekinesis could prove very useful in the labyrinth, as there are many trapped doors and chests that could be safely opened from a distance. By exerting greater force, at a cost in fine control, creatures can also be pushed away from the caster.