Dunamancy

 is the ancient and esoteric study of the magic called dunamis which is based on potentiality and probability. Matt Mercer on Dunamancy - Explorer’s Guide to Wildemount for D&D Dunamis was discovered independently by several nations and explored to manage and control time, gravity, and fate, removing chance from mortal actions.

Description
Dunamis is "the primal magical energy of potentiality and actuality, an anticipatory arcane force that helps shape the multiverse and might very well be what holds its elements together, like an infinite web of unseen tethers. Those who study to control and tap into Dunamancy can subtly bend the flow of time and space by controlling the forces of localized gravity, peering into possibly timelines to shift fate in their favor, and scattering the potential energy of their enemies to rob them of their potency."

The Beacons' Origin
When the Luxon arrived in Exandria, it discovered the Primordial titans, born from the elemental chaos. They fought, which led the Luxon to believe that there was no consciousness in the elemental chaos and that souls were lost to the darkness. The Luxon broke into scattered beacons that would enact a cycle of rebirth for those who were bound to its light in hopes that those beings would gradually learn and mature, and one day something would find and reassemble the Luxon.

Aeorian study
Before the Calamity, residents of Aeor found at least one Luxon beacon, provided them with a source for comprehensive research. Athodan was focused on the field of rejuvenation, working on the Factorum Malleus Project, which loosely translates in common as Hammer of Creation.

In his researh, Ayoshadaf from the Genesis Ward of Aeor explored the transmutation aspect of the artifact and influence on the passage of time. They discovered one could temporarily shunt to a point in one's history or even move beyond it, leaving an anchoring echo behind. Individuals who spent more time in the past than predetermined had their echoes fade to the point where the person would disappear. Scientists named this research the T-Dock Project or Temporal Dock.

Centuries later, Caleb Widogast and Essek Thelyss, one of the few individuals who knew of this expirement, both decided not to utilize its powers, changeing the tragic events happened with Caleb's parents, Leofric and Una Ermendrud, but terminate the research. Caleb used Disintegrate to destroy everything in the chamber.

Kryn Dynasty and Consecution
The Kryn Dynasty has found four pieces of the body and named them the Luxon beacons. These relics became critical to the Dynasty's study of dunamancy, allowing them to learn how to manipulate gravity, entropy, and time.

After the discovery of the beacons, the principal Kryn Dynasty dens learned how to connect a soul to a Luxon beacon and named the process "consecution". When a consecuted creature dies within one hundred miles of a Beacon, its soul does not move on to the Outer Planes; rather, its soul is reborn in a newborn infant within one hundred miles of the Beacon. Around adolescence, the creature carrying the consecuted soul begins to remember their past life and be strongly drawn toward Xhorhas and the source of its returning memories.

Cerberus Assembly Research
In Dualahei 836 PD, the Dwendalian Empire discovered a beacon in the ruins of Shattengrod outside of Pride's Call. The Cerberus Assembly, working within the Soltryce Academy and experimenting with time and reality, also uncovered the principals of dunamancy. During their study, the Assembly hired Yeza Brenatto in Felderwin to attempt to extract the power of the dunamantic field from the beacon and distill it into a potion for millitary purposes. His experiments resulted in large areas of people surrounding the apothecary he worked in to feel sluggish or move at unnaturally fast speeds. Yeza eventually was able to distill a single vial of dunamis power and there were plans to make more, even considering the costly and time consuming process.

Trent Ikithon of the Cerberus Assembly had found some students who showed signs of being skilled at Dunamancy and grounded his own laboratory in the Vergesson Sanatorium, where he was conducting research on a Luxon beacon.

War of Ash and Light
 The Mighty Nein gave the vial of distilled dunamis they recovered from the Brenatto apothecary to Essek, who was interested in studying it. Essek also told the Nein about two known cases of time travel using Dunamancy. In one instance, the subject never returned, and in the other, the caster returned but immediately turned to dust.

Dunamancy utilazation history
 After emerging from the worm tunnels into Xhorhas, the Mighty Nein were ambushed by a pack of gnolls, a Kryn Dynasty warrior, and a mage. The mage cast two dunamantic spells- Compress Gravity and Vacuum Blast.

 Essek Thelyss taught Caleb two dunamantic spells during his visit in the episode. He mentioned spells that revolve around density and gravity (referencing the subfield of Graviturgy) as well as fate, destiny, and potentiality (referencing the subfield of Chronurgy). In the end, Caleb chose to learn about fate and Essek taught him two dunamantic spells: Fortune's Favor and Gift of Alacrity.

 Essek escorted the Mighty Nein to their visit with the captive Scourger. When she attacked Caleb, Essek killed her with a dunamantic spell (likely Gravity Sinkhole). Back at the Xhorhaus, Caleb persuaded Essek to teach him two more Dunamancy spells: Immovable Object and Resonant Echo.

 Caleb used Gravity Sinkhole- reverse engineered from when he had seen Essek cast it- numerous times in the Mighty Nein's robbery of the Vergessen Sanitorium.

 In the fight with the frost salamanders, Essek cast Magnify Gravity. In preparation for setting the Intuit Charges, Caleb and Essek both cast Fortune's Favor. Essek and Caleb both cast Gravity Sinkhole during the fight with the Aeorian hunters.

 While investigating the Genesis Ward, the Nein found the Rejuvenation Chamber, Essek and Caleb sensed dunamis energy. When Fjord used one of the rejuvenation terminals, he got the benefit of a long rest even though only a few moments had passed. The aura of dunamis in the chamber increased strongly as time was accelerated within the cylinder. Caleb entered the cylinder but it appeared to be out of power. Essek inspected the purple gem on the second, damaged terminal and called Caleb over, pointing out that within it appeared elements of space and drifting possibilities, like a smaller, weaker Luxon beacon. Essek then used magic to destroy the cylinder, releasing the diamond-shaped dark purple gem, which he gave to Caleb.

In preparation for battle with an Aeorian nullifier, Essek used the Chronurgy subclass feature Arcane Abeyance to store the spell Lightning Bolt in a bead, which he gave to Veth.

 When the Mighty Nein were concerned about having no time to rest before facing Lucien, Essek suggested using dunamancy and the crystal they had taken from the Rejuvenation terminal to create a skip in time, granting the group the benefits of a long rest. With Caleb’s help, Essek completed the experimental spell, destroying the crystal and reinvigorating the party.

 In preparation for the fight with Lucien, Essek cast Fortune's Favor on himself, Caduceus, and Jester. He used Arcane Abeyance to store the Haste spell, and gave it to Yasha. During the battle itself, both wizards cast Gravity Fissure.

 Essek cast the spells Tether Essence and Gravity Fissure in the battle with the Somnovem Omega.

 When Trent Ikithon attacked the Mighty Nein, he was wearing a necklace of condensed dunamis energy, which he used to cast Time Stop.

Trivia

 * Dunamancy and its unique spells are a homebrew creation of Matthew Mercer. It now appears in Explorer's Guide to Wildemount, making the spells and classes included there official content.
 * Although some spells (like Reverse Gravity) are not considered part of the dunamantic studies, it is believed that facets of this magic are blended in their essence. Trent Ikithon proved this by using condensed, manufactured dunamis energy to cast Time Stop.
 * Dunamis appears to heavily rely on a notion not entirely unlike the Many Worlds Interpretation of quantum mechanics - that multiple versions of us exist based on possibilities explored or left to explore across multiple timelines. Each of the members of the Mighty Nein, save Mollymauk Tealeaf, who opted never to use the beacon, have experienced this sensation in their use of the Fragments of Possibility. However, having much more experience with this magic, the Kryn echo knights and dunamancers seem able to call upon their alternate selves to aid them in battle, in the forms of shadowy echoes.
 * "Dunamis" is the classical pronunciation of the Greek word δύναμις (dynamis), meaning "power", "potential" or "ability", and is central to the Aristotelian idea of potentiality and actuality.
 * Matt revealed in the  that if Essek and Caleb had failed the check to get a long rest with the dunamis crystal, rather than getting a long rest instantly, the party would have been sent one day forward instantly without any rest.