Teshin is the Conclave Master, who resides within the Conclave Hall of the Relays. He is responsible for the management of the Conclave PvP System, providing incentives through various rewards that can be earned through Conclave battles, as well as The Steel Path game mode.
Teshin is an individual from the Orokin era, who was one of the few who did not enter cryosleep. How he has remained alive for this long however, is unknown. He blames the fall of the Orokin on the Lotus, who led the Tenno to become complacent like oxen.
Teshin references the imminent arrival of the Sentients by insisting the Tenno use the Conclave to fight their greatest enemy, themselves, in order to grow stronger and to prepare themselves for 'horrors' beyond the Outer Terminus.
After the Lotus abruptly breaks off communication with the Tenno, Teshin makes contact, offering to guide the player and help them figure out why. By the time the Lotus resurfaces, the Tenno and Teshin are already hot on the trail of Tyl Regor and his excavation team.
Notably, Tyl Regor calls Teshin a "pseudo-Tenno," and implies at least some familiarity between the two.
During this quest, it is revealed that Teshin is one of the Dax Soldiers, bearing the epithet "Teshin Dax", one of the mighty warrior caste created by the Orokin and used as their personal guardians. Unfortunately for him, the Elder of the Grineer Queens possesses a Kuva Scepter, marking her as a member of the Orokin Elite. As result of his Dax heritage, Teshin is mentally incapable of refusing her orders, though his loathing for the Twins is made quite clear.
In the quest, Teshin suggests that Margulis did a disservice to Tenno by concealing and erasing their past. Partly to rectify this and partly to save the player's life, Teshin guides the player's Operator (via astral projection, it is assumed) through a mountain temple on Earth, to an Orokin Yuvan Theater previously used for countless Orokin Continuity rituals. Thanks to Teshin's guidance the player's Operator regains full use of their powers, and transfers into the Kuva Fortress using their Warframe. In the ensuing battle the Queens' Guardians and Teshin are defeated, and the Elder Queen loses possession of her Scepter, freeing Teshin from her thrall.
Teshin is one of the characters that will be controllable by the player during the quest, armed with an and his daishō. During the Sentient invasion, Teshin infiltrates a Murex, destroying an Aerolyst in the process, to search for scattered Orphix fields, with the help of Ordis, and disable them. Teshin tells Ordis that he doesn't need his help, and orders him to switch off.
Teshin can infuse his Nikana daishō with elemental damage to deal more damage to Sentients, and can change the elemental damage type, with , , and available. Changing the damage type also changes the Stance of his weapon, between Carving Mantis for Heat, Crossing Snakes for Cold, and Swirling Tiger for Electricity. He can also throw his Orvius to damage Sentients and destroy objects, or grapple to it in the air for faster traversal and crossing gaps, and he takes no fall damage.
On his way to an Orphix field, Teshin encounters captured Grineer soldiers, and a large Kuva-like object, and he feels unwell. Next to an Orphix field, Teshin encounters more Sentients and he destroys them, but the field is shielded. Ordis dephases the shield, allowing Teshin to destroy the field. Ballas sends a transmission to Teshin, realizing that the Tenno have sent him on the Murex, and ends the transmission saying that "they're both relics". After the transmission, a large Sentient appears. Teshin downs the Sentient, ready for a Finisher, he slashes it, grabs its orb and destroys it, and he says "too easy". The events that follow are unknown.
- His voice actor is Sean Phillips.
- His helmet makes him look similar to a Kappa, a Japanese mythological water imp with a plate full of water on the top of its head.
- The style itself is also reminiscent of a kasa, a traditional Japanese hat commonly worn by monks and warriors.
- Teshin is the second syndicate leader to have multiple intro voice lines, with the first being Cephalon Suda.
- He wields a and a Nikana shōtō (a pairing known as a daishō), both having Gemini Nikana Sheaths. He is also able to call his blades to his hands in the event he is disarmed as indicated in the War Within quest.
- Teshin is likely derived from Deshin Shekpa, the 5th head of the Kagyu school of Tibetan Buddhism.
- During Tennocon 2021 it was revealed that Teshin will be one of three playable characters in the next phase of The New War.