History of Magic (The Folly of Karsus)
In an ancient and often referred to the tale of the battle between the powers known as Selune and Shar, the goddess Mystryl came into being. Mystryl was the goddess who first manipulated the Weave in order to facilitate all magic in Faerun, and she was said to teach the first spellcaster. Magic and the practice of magic and spells thrived in the times that followed, as schools of magic specializing in specific areas of focus emerged and developed over time.
Due to the folly of a Netherese Wizard known as Karsus, Mystryl died and the Weave was not able to be maintained properly- this caused all magic to fail for a time, even divine magic, as the Weave is needed to serve as the conduit between the prime material plane and all other planes.
Many additional events and strange happenings since the death of Mystryl have influenced the landscape of magic in the realms. When a gnome stole a glance at one of the Nether Scrolls so many generations ago, and that knowledge was shared with other gnomes alive at the time, their race acquired their talent for illusion craft. Dragon magic has always been known as a supreme form of illusion magic, as well. Elves owe their resistance to enchantments from their reverie; their introspective meditations seeming to grant them resolve and mental fortitude when confronted with magic that would twist the mind. The elves also developed divinations so they could confront the Alunsree, their word for Doppelgangers, who were trying to infiltrate their society while humans were still living in caves. The peoples of Faerun have continually utilized magic to adapt and survive, with a few exceptions such as the dwarven races or the copper elves of the Wealdath, who somewhat shun arcane magic in particular.
Only in relatively recent times has a darker, dangerous “shadow” weave availed itself, this creation belonging to the goddess Shar. The individuals who study this dark shadow weave typically do so in secret, and magic worked via the power of this subversion of the Weave were undetectable by others, having no signature or imprint upon the actual Weave.
Practitioners of Magic
All beings that work magical spells and phenomena make use of the Weave. Dragons, sorcerers, and many types of creatures have an innate connection to the Weave, as do women, in general, more so than men. The Weave itself may even be related to the power that radiates from living beings and it could be intrinsic to the nature of life itself.
All character classes which use spells, whether divine or arcane, are using the Weave. The specific rituals and methods that practitioners of magic utilize vary widely but follow a strict series of rules. Magical power will be limited, stored in the memory, and forgotten once accessed. It would require specific components and perhaps even offerings to appease the beings in distant planes who were involved in the manifestation of the power. In the case of wizards, spells must be learned through the intensive and often onerous study of patterns and formulas and universal laws that are nearly impossible to convey to the common peasant. In the case of priests and other divine casters, spells of the first and second spell level are a result of a character’s faith and rituals; it is later spell levels that are granted expressly through devout prayer and intense veneration.
Other practitioners of magic yet exist, including warlocks or even spellfire channelers, whose interactions with otherworldly powers or with the Weave itself are poorly understood even by the sages. Just as clerics can fall into disfavor with the beings that grant their powers, so too can warlocks and blackguards run afoul of their respective patrons. The paths to power and the very open nature of the Weave enables all of these things and more to take place, and while it is well known that rebellious clerics will lose their divine powers, only very rarely does Mystra restrict a being from utilizing her Weave.
Deities of Magic
Mystra is the foremost deity of magic, known as the One True Spell. She is served by Azuth, who was once a mortal and who served Mystra as her first Magister. Azuth is the god of Spellcasters, whereas Mystra is the goddess of spells and magic itself. Azuth is served by Savras and even Velsharoon serves in this group of deities of magic. Other deities of magic include Corellon Larethian and Sehanine Moonbow of the Seldarine and to a lesser extent Selune.
Through the Weave, magic may be infused into items which carry magical power. This process is always draining upon a wizard or other spellcaster, and it is said that all new items are weighed and judged by Mystra before coming into being. Magical items range from helpful and providing ease or daily utility in places like Calimshan where such wares are more common, to items that contain slaying spells, illusions, and glamours that make armors look like simple clothing, and everything in between.