Time travel

Time travel was th means by which an individual, a group of people, or even an entire city could travel backward through time to experience a previous year in any time decades or even centuries prior. They could see their home as it was years past or even visit an ancient civilization of which they were only somewhat familiar. It an extremely difficult and demanding feat that came with great risk to anyone involved.

Restrictions
Time travel was strictly regulated by Mystryl, the ancient goddess of time and magic. In the ages before the fall of Netheril she allowed no being to change the "stream of time" save for a single manner of her choosing, the time conduit, and was omniscient to any anomalous events that attempted to bypass her law.

These limitations continued under the goddess' successors, the two incarnations of Mystra, and her allies Oghma and Deneir, for at least the next 1700 years. She lent certain powers to her daughters the Seven Sisters, along with a select few of her chosen and other great spellcasters, to empower them to help monitor chronomancers in Faerûn and prevent them from changing or creating any new timelines.

It was impossible for a being to travel in time on another plane of existence, specifically the Demiplane of Time, and then return to the crystal sphere of the planet Toril, or its predecessor Abeir-Toril.

Consequences
It was believed by many sages that if an individual altered a crucial or decisive event, they could alter the "stream of time" and begin the formation of a new timeline, one that could be markedly different from the one they have known. It was believed that travel from one timeline to another was wholly impossible even for the gods, as they could not perceive of such different realities.

Some scholars believed there was some unperceived power greater than the gods that scrutinized these alternate timelines and made it their duty to ensure their wholeness.

Usage
Time-manipulation and time travel were often used by chronomancers, practitioners of arcane magic that focused on their own specific school of magic called chronomancy. These individuals tapped into the Temporal Prime, what they referred to as the "timestream", a directed flow of currents formed by collective lives and experience within a certain population.

Most chronomancers native to the Realms were devotees of either the goddess of Mystra, or of the deities of history, Deneir and Oghma. In most instances they were devout guardians of historical knowledge and used their powers solely to gather information.

Spells
The primary magical means of time travel was time conduit, an ancient chronomancy spell created by Mystryl that opened temporary portal to another time. The caster and their allies could venture through the conduit to a time and realm with which they were at least moderately knowledgeable, under the safeguards placed forth my Mystryl. Their journey would last for the duration of one year exactly, beginning on the year's first day and ending on its last. No individual could later return to that same year, lest the anomaly be detected and they were violently shot back in time up to an entire century, hundreds of miles away.

The time conduit spell required specific knowledge of the year or era during which the destination time occurred. As such, there were no signs it could be used to travel forward in time.

While it was believed by some there were magical means to bypass the restrictions of the time conduit. a spell originating form ancient Netheril belayed that notion. The transmutation spell teleport through time allowed a select group of people to travel back in time thousands of years, albeit with some temporal shift in their exact desired destination. It was possible that a being casting teleport through time could even encounter another version of themself in the same timeline. The explanation for this apparent exception to Mystral's precise temporal rules remained unexplained as of the 14 century DR.

Portals
The Realms were home to at least five time gates, permanent portals that allowed for time travel, and two very different portals that allowed for some limited form of time travel. As was demonstrated in at least one specific occurrence, the knowledge to create new portals was not entirely lost to time.

Three time gates were recorded by the ancient of scholars of Mystryl, whose studies back to the time of ancient Netheril:
 * A cave set deep within the Spine of the World mounts in the North.
 * Atop the toppled apex of Misken's Peak, frozen beneath the Great Glacier.
 * In a cave within Mount Andrus in the Vilhon Reach; current whereabouts unknown due to an erroneous transcription of the locale as "Andrio's Peak".

The fourth time gate known only ten elves of the city of Chrysalis:
 * Within a cave beneath a waterfall that fed Mirror Lake in Synnoria.

A fifth time gate reconstructed by the Imperial Society of Historial Study for use in their study of ancient history:
 * Hidden inside a monastery set deep within the Orsraun Mountains in Turmish.

The constantly moving whirlpool associated with the goddess Umberlee:
 * The mysterious vortex called Umberlee's Fist was actually a traveling undersea portal that transported vessels across great distances, and due to its poor temporal anchoring, occasionally back in time.

Finally, a malfunctioning portal created by an unnamed and unconventional wizard:
 * Found in Triel, the one-way portal operated by Conrath Isthan would sporadically and repeatedly send its "passengers" centuries in the past to a singular moment, the summoning forth of a balor somewhere on Toril.

Items
At some unknown time and place, a group of powerful spellcasters known as the Weavers the first of the black obelisks, powerful magical artifacts that were capable of transporting an entire city back in time. The knowledge of their creation eventually passed down to the arcanists of ancient Netheril, who crafted a number of them for use on their great flying cities. Mystryl's restrictions did not appear to affect this mode of time travel, as it was entirely possible to travel back directly to the beginning of Spring in some past year.

After the fall of Netheril, the remaining black obelisks remained scattered across the Realms. Known locations of their discovery included the Tomb of the Nine Gods in Chult, the great dungeon-complex of Undermountain, within the tunnels beneath Gracklstugh in the Underdark], the ruined necropolis of Ythryn beneath the Great Glacier, and even out on the open lands of the Sword Coast North.

History
The legendary arcanist Jeriah Chronos was born in the in the, a date birth marked the beginning Netheril's Golden Age. The vain arcanist would formulate and craft his first time-manipulation spell a mere 68 years later, and begin the school of magic that carried on his name and legacy. Over the course of his life he became increasingly concerned about the arcanists' collective arrogance, believing that it would be the undoing of their great magocratic empire.

At some point during the first three millennia of the Age of Humanity, the arcanists of Netheril recovered the specifications of the black obelisks originally created by the Weavers. They crafted a number of these powerful artifacts as a means to circumvent any catastrophic consequences they may have befell their empire. There was no recorded evidence that any of the obelisks were successfully used in that manner.

The last known journey to recover one of the time gates was recorded to have occurred in the.

Appendix

 * Adventures
 * Chronomancer