The mysteries of Yoda and his kind permeate the lore of Star Wars. Although Grogu has thoroughly claimed the hearts of fans, it's Jedi Master Yaddle who watches over some of their strangest secrets. Yaddle's place on the Jedi Council is left obscure in the films, but some Legends lore reveals she's surprisingly attuned to hidden Jedi powers. One of those powers, morichro, could be deadly in the wrong hands.
The art of morichro has a scant place in the canon, listed only in Simon Beecroft's updated Star Wars Character Encyclopedia as one of Yaddle's secret teachings. The technique seems like the usual light side of the Force, Buddhist-themed fare at first. It's a method of controlling and even stilling the body's critical functions, similar to being in an extended trance-like state. But morichro goes much further than that. It's a targeted art, and it can be weaponized.
Morichro Is the Most Chilling of the Jedi Arts
Though its deadlier form is never shown against a sentient being in Legends or canon, the explanation of what morichro can do is chilling. A Jedi armed with this art can pause their opponent, shutting off their body against their will. The target might realize that their breath slowing, unable to panic. Their blood would turn sluggish, and their thoughts would freeze. Used to its fullest, the Jedi can outright stop someone's heart. If the Jedi forgets to monitor their prisoner, morichro can lull its victim all the way down into a slow, starving death.
It's a surprising thing to find something like this marked as a canon Jedi ability, but its introduction may hold the key as to why. Morichro is first mentioned in the fifth issue of the defunct magazine, Star Wars Gamer, in an article titled "The Emperor's Pawns." Abel G. Peña is listed as the primary author of the article, but his co-author is Juan Schwartz, then a pseudonym for Star Wars creative executive Pablo Hidalgo, whose job is defining what is and what isn't canon.
Non-canon Legends sources show morichro in action, but even there, it's scarcely described. Kyp Durron, Luke's one-time apprentice, utilizes it safely on himself to survive in Kevin J. Anderson's novel, Champions of the Force. Master Yaddle's personal link to the technique is more obscure. The out-of-date text, Jedi vs Sith, indicates that Yaddle rediscovered the ancient technique from a series of holocrons that recorded a great schism within the Order, but it's not clear when she accomplished this.
Meanwhile, Star Wars Tales #5 included the non-canon story, "The One Below," by Dean Motter and Jesús Saiz. In this short comic, Yaddle survives a century of imprisonment below the surface of the planet Koba, and it's suggested she used her Force powers to manage it on the few supplies she was granted. The art of morichro would be a logical tool in her arsenal, but it goes unnamed here. Nonetheless, in time she escapes. With her signature kindness and patience, she remains among her once-captors long enough to help stabilize the war-weary folk before returning to Coruscant.
Jedi Master Yaddle is one of the oddest characters to come out of the prequel era. Instead of becoming an outlet to explore the legend of Yoda, she's mostly unexplored in canon today. Her post-Council fate was a mystery for some time, the only clue that she was gone being her Force ghost appearance in a series of visions Vader faces in the Darth Vader: Dark Lord of the Sith comics. Disney+ anthology Tales of the Jedi did finally confirm what happened, with Yaddle meeting her end at the hands of a vicious Count Dooku. At least Star Wars Jedi: Fallen Order gave her a trace of respect, with the Lateron pilot, Greez Dritus, recalling her legend with fondness.