Polycosmic Manipulation is a special ability developed prior to the Third Sack. Based on Polycosm (Multiverse) theory, which is similar to the Many Worlds interpretation of Quantum Mechanics, polycosmic manipulation involves understanding consciousness as a path, (known as a world track or "Narrative,") through the Hemn space of all possible realities, and being able to manipulate that path for yourself and those around you.
The technique was developed in certain Millenarian Maths in the period prior to the Third Sack when these Maths were used as storage facilities for the Saecular Power's nuclear waste. To avoid damage to their cells from the nuclear radiation, the Avout developed techniques to change their "Narrative" to one in which the quantum events of nuclear decay avoided damaging their bodies. This technique was later refined to allow the selection of Narrative where cellular decay due to aging did not take place, allowing those who mastered the skill the ability to live for centuries.
Avout skilled in this technique became known as Incanters and Rhetors in Saecular legends. The Incanters were alleged to be able to change reality through words, while the Rhetors were alleged to be able to change the past by changing memories and records. These descriptions are probably inaccurate. In spite of the Concents have been forbidden most technology after the Second Sack, polycosmic manipulation gave the avout considerable power using just their minds, and fear of this is speculated to have been the cause of the Third Sack. However, the Maths where the technique was developed were left alone during this sack.
Fraa Jad is an Incanter. He states he has the ability to experience multiple Narratives at the same time, and appears to have the ability to move his consciousness, and that of his companions, into ones he chooses.
The Urnud also develop a Polycosmic technology by accident, when they attempt to send their habitat ship, the Daban Urnud back in time. Instead the ship is transported to a different cosmos with different physics, yet with remarkably similar beings and history. They developed the technique so it could be used reliably.
The Avout, at the time of the Third Sack, may also have developed a method to transmit information into another cosmos. In particular, the Daban Urnud received messages appearing to depict the Third Sack, and this caused their attempt to travel in time. This two-way transmission of information between Urnud and Arbre contradicts the strict one-way rule of Complex Protism, but this contradiction is never explicitly resolved. One possible interpretation is that the Urnud world is farther down in the Hylaean Flow stream than Arbre. When the Urnudians try to travel to the "past" (time is an illusion created by the one-way Hylaean Flow) they actually travel "upstream," or to successively more Hylaean cosmi. This follows as well from the description that Jules Verne Durand gives of the various differences between the four cosmi represented on the ship.
Exactly what Rhetor ability allows is never explicitly revealed.
Other students of this field include Fraa Paphlagon, Fraa Lodoghir and Fraa Orolo. Through the latter's teaching, Erasmas learns about the field. It is uncertain if any of these become Incanters or Rhetors, only Jad actually demonstrates the skill.