Dunamancy

 is the ancient and esoteric study of the magic of dunamis.

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 this near-invisible power 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."

Chapter 11
 While spending down time in Archive of the Cobalt Soul in Zadash, Caleb Widogast researched methods of controlling time. He discovered information about some newer arcane experiments being conducted by the Soltryce Academy in Rexxentrum. A newer magical energy seemed to have been discovered, or possibly rediscovered, from the Age of Arcanum. This energy was being referred to by the Soltryce mages as "Dunamis". Other than that, there was very little information: anything else was the proprietary knowledge of the Academy.

Chapter 13
 While searching the basement of Yeza Brenatto's apothecary in Felderwin, the Mighty Nein found notes of a Cerberus Assembly researcher. The Assembly had been doing experiments with a beacon. The "dunamis field" from the experiments had covered large areas, causing people to sometimes feel sluggish or move at unnaturally fast speeds. The Kryn Dynasty of Xhorhas had the ability to use Dunamancy to manipulate gravity, entropy, and time. The Kryn had been researching its use for centuries in Ghor Dranas.

It had been difficult for the Cerberus Assembly to create an object that could sustain the energy of a dunamis field. Yeza Brenatto had been working with the Cerberus Assembly and distilled one vial of dunamis. They had plans to make more once they could find a way to produce them without using a Beacon directly. The notes said that Trent Ikithon has found some students who showed signs of being skilled at Dunamancy.

 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.

Chapter 14
 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.

Chapter 15
 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.

Chapter 16
 The Mighty Nein were shown to Trent Ikithon's lab in the Vergessen Santitorium, where he was conducting research on a Luxon beacon.

 The Mighty Nein gave the vial of distilled dunamis they recovered from the Brenatto apothocary 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.

Chapter 18
 Yeza elaborated on his time working for the Cerberus Assembly, Vess DeRogna specifically. Yeza said that he didn't fully understand the arcane aspect of the dunamantic potion he created as much as the alchemical aspect.

 The Mighty Nein reunited with Essek Thelyss at Vurmas Outpost. He told the party that delvers into Aeorian ruins had discovered iconography resembling a Luxon Beacon, and that there was further evidence to suggest that the Aeorians had been experimenting with dunamis before the Dynasty was even established.

Chapter 19
 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.

 Trent Ikithon recognized that Caleb had used dunamantic spells, and implied that he had deduced that Caleb had been taught by Essek.

 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 a records room in the Genesis Ward, Caleb found notes that discussed an individual named Athodan who had discovered "The Relic." The Nein proceeded through the Ward to the Rejuvenation Chamber, within which 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.

 The Mighty Nein discovered the lead-lined Temporal-Dock chamber in the Genesis Ward, which contained many arcane devices. The central platform of the room used sigils from both the Transmutation and Dunamancy schools, particularly those for temporal alteration. Caleb found notes referring to the "Primal Artifact" with a drawing of a Luxon beacon, indicating that the Aeorians learned from the beacon how to travel backwards in one's own timeline, leaving an anchoring echo behind. The Temporal Dock allowed the Aeorians to spend only a few seconds in transit, but created worrying physical stress. Individuals who spent longer than predetermined in the past had their echoes fade and the person never returned.

 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. When Caleb and Essek returned to the Temporal Dock in Aeor, they both decided not to go back in time, and Caleb used Disintegrate to destroy everything in the chamber.

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.