The Ritual of Usurpation is a Dark Ages True Magick ritual devised by the Order of Hermes Archmage Goratrix of House Tremere. Performed in 1022 CE at Ceoris Castle when he and the rest of the participating leadership of House Tremere were still in possession of their Avatar's as awakened mortals. The ritual's asserted aim was not only an attempt at obtaining immortality for its participants, but in so doing preserve their abilities to work True Magick. It succeeded in fulfilling the first of its professed aims, but utterly failed at succeeding in the second. Instead, at the conclusion of the ritual, the Avatars of those involved were irrevocably shattered, and the leadership of House Tremere awoke from unconsciousness unable to perform True Magick as newly born members of the vampiric race known as Kindred. In the ensuing years, the Vampiric Discipline of Thaumaturgy, a specialized form of Blood Magic informed by their millennia of wisdom and experience as workers of the Sphereic Arts became their primary outlet for their Ritual Magic and Sorcery, in the form of Paths.
A Dark Origin
In the year 1000, frustrated with a lack of progress in his research and experimentation in resolving the lessening of True Magick in the world, Goratrix turned his attentions to the tales of dark immortals that roamed the Carpathian wood of Transylvania as a possible solution. Resolved to determine what if any possibilities for a remedy existed therein, he spent years investigating arcane texts, and sending various acolytes out to comb the countryside for information on the Children of the Night. In response, local fiends left the severed head of his fellow Mage Arundinis at the threshold of Ceoris in 1005 CE. Unfazed from his aims, Goratrix employed a necromantic ritual to relive the last days of Arundinis' life. Arundinis had been captured and tortured into revealing the secrets of House Tremere and its endeavors by the Elder vampire known as Roland, childe of the Tzimisce Voivode Vladimir Rustovich. Now having the proof he had been looking for, Goratrix petitioned Tremere himself for permission to raid the haven of Roland and take him prisoner for purposes of experimentation, information and reprisal. At great cost, Roland was taken by the war party under the leadership of Goratrix, and in time, he too met a similar tortured and murderous fate as that of Arundinis, but not before Goratrix had forced Roland to Embrace two of his own apprentices, the unsuspecting magi known as Stephen and Pharus.
After years secreted away in the seclusion of Goratrix's private suite and workshops, Stephen and Pharus were all but forgotten by the rest of House Tremere. Failure greeted the works of many others in House Tremere endeavoring to confront and solve the problem of Magick leaving the world. Eventually the Mage Epistatia was recruited into assisting Goratrix in his secret experiments involving the young neonates to crack the mystery of their immortality towards achieving his own ends. This work was not without difficulty, as obstacles eventually led to Goratrix needing to yet again enter into a dark pact with the "Root Of All" (the demon Kupala) and "Stars Beyond" (the Antediluvian known as Saulot) in order to make any advances, all while Ponticulus, the World Tree of Ceoris, watched his every damnable, dark and duplicitous act.
In 1022, Goratrix was finally ready to reveal his findings. He invited the necessary select few from House Tremere's leadership to aid in performing the complex Ritual of Usurpation, at the climax of which the Cainite neonates Stephen and Pharus were wholly consumed and destroyed by the gathering of Archmages. Upon awakening from the ritual, its participants Tremere, Meerlinda, Etrius, Calderon, LeDuc, Goratrix and two others discovered in the aftermath that their Awakened Avatars had been shattered and they now were all, to a person, members of the Damned, doomed thereafter to a blood soaked and thirst filled unlife. Only Goratrix was unsurprised by the actual outcome, to such an extent that Calderon in a fury attacked him, until Tremere intervened for calm, sensing that indeed a new form of Dark Power had been obtained with even more on the horizon as members of undead.
A bit of deductive (dis)continuity puts into question many of the concrete materials regarding the transition of House Tremere to and the origins of the Tremere as a Clan, and the power of its Founders. For one, it was not Seven conspirators that initially turned themselves into vampires but Eight. To quote:
"In 1022, Goratrix announced to a select few that they were needed to aid him in his final experiment. Invited to join him [sic] Goratrix [sic] were Tremere, Etrius, Meerlinda, and four other of our founder's closest associates."
Furthermore, there is the question of Vampiric Generation. Goratrix's Ritual of Usurpation that begat the founders of the Clan Tremere as kindred in 1022 CE involved the sacrifice and consumption of two Tremere apprentices to Goratrix, Stephan and Pharus. Both of whom had been embraced by the Tzimisce Elder Roland at the behest of Goratrix just prior to Roland's destruction by the Archmage. Though the in game and plot mechanics of the Ritual of Usurpation are unclear, it is speculated that it either is a ritual of Embrace that would result in one being the childer of the sacrificed, i.e. a generation removed, or becoming a vampire of equal power (generation) of the one(s) sacrificed in this manner. As such, the core of the Tremere Clan, its founders at their becoming would all have been either of the Ninth or Eighth Generation respectively. Both Pharus and Stephan, as they were embraced by Roland, a Tzimisce of the Seventh Generation, not made into vampires as a result of a ritual, they both were upon the advent of their undeath of the 8th Generation. There is no apparent evidence of diablerie in the sanguinary line of Roland, Childe of Vladimir Rustovich, Childe of Kosczecsyku, Childe of Yorak, Childe of The Eldest (the Tzimisce Antediluvian). Nor is there any evidence of diablerie in the Final Death of Roland at the hands of his torturer and jailer Goratrix, so the numbers as it were, are quite clear.
Additionally, it is not until 1126 through 1133 CE that diablerie as a mechanism for an increase in one's power as a Cainite was even discovered by their clan founders. During this period, Etrius and Tremere alone engaged in a campaign of grotesque diablerie for a short period hunting down Methuselahs of various clans to drain their unlife's blood and thus increase their own power. After their first success in dispatching a Methuselah in Rome, Tremere and Etrius began to carefully plan any future assaults so as to include the other Councilors (Clan Founders) to join in the kill. It was in 1133 that the tomb of the Antediluvian known as Saulot had been discovered by Tremere himself, and the House Tremere truly ascended to the level of a Clan, presumably with a founder of their own at its head, newly empowered by the stolen vitae of the fallen third generation ancient. The ultimate fates of Tremere and Saulot, Etrius and Goratrix however are a tale for another time. Nonetheless, what is clear is that a significant amount of diablerie, far more than previously suspected or asserted had to ensue among the Clan's founders for them to have obtained the power of a fellow Methuselah.