Chi blocking is an ancient technique that has been practiced in secret for centuries. It is a special ability that Ty Lee, and later the Equalists, utilized in combat against their enemies. Blocking someone's chi renders the victim's muscles useless and temporarily disables a bender's abilities. This earned Katara's fear and spite after Ty Lee blocked her chi in Omashu. Chi blocking is mainly used by nonbenders as a way of self-defense or even an attack form.
The first time anybody in Team Avatar experienced chi blocking was when the group first met Mai, Ty Lee and Azula, who began to attack Aang, Sokka, and Katara, after breaking a deal to trade King Bumi for Tom-Tom. During the fighting, Ty Lee blocked Katara's chi, rendering her bending useless. However, Sokka arrived and used his boomerang to free his sister, allowing the group to escape. From this point onward, the group of girls began hunting down the Avatar.
The group of girls then began to pursue Team Avatar by following Appa's trail of shed fur in a giant machine. Eventually, Team Avatar figured this out, and they separated. Mai and Ty Lee chased down Katara and Sokka on the shores of the Nan Shan River. They fought the duo - Mai dealt with Katara, while Ty Lee attacked Sokka, rendering most of his limbs useless.
Later, the trio of girls led an attack on Ba Sing Se through a drill. Ba Sing Se's Terra Team attempted to stop the trio, but Mai and Ty Lee took them down with ease. Ty Lee dealt paralyzing chi blocking blows to anyone who attempted to fight her. Katara attempted to heal the fallen men, but said that they had been completely cut off from their chi, and she could not help them.
However, this gave Sokka an idea. He said that Ty Lee took down people by hitting their weak points, and that perhaps the drill worked the same way. Using Toph's earthbending, the rest of the team tunneled under the drill. Using its "weak spots", similar to the idea of chi blocking, they destroyed the drill.
Later, the trio tracked down Appa once more and discovered that the Kyoshi Warriors were with them. A battle ensued, during which Ty Lee utilizing chi blocking to immobilize her opponents. The technique was used yet again after the trio invaded Ba Sing Se disguised as Kyoshi Warriors. Katara came to them after seeing Zuko searching for aid, but once again, Ty Lee paralyzed her, catching her by surprise. She also immobilized Sokka and Toph when Azula threatened Earth King Kuei with her firebending, forcing them to surrender.
The technique was utilized by Ty Lee once again on Ember Island, when she was cornered by several boys at a party hosted by Chan. Feeling threatened by all of them crowding around her, she used chi blocking to free herself.
Ty Lee was later taken to the Boiling Rock prison with Azula and Mai during Sokka, Zuko, Hakoda, and Suki's escape. The trio pursued them onto a gondola, which resulted in another fight between the two groups. Ty Lee attempted to chi block Suki, however, the Kyoshi Warrior was able to avoid the attacks after learning from past experience. Later, when Mai and Azula prepared to fight after the former betrayed Azula by saving Zuko, Ty Lee used chi blocking to paralyze Azula and temporarily block her bending in an attempt to protect Mai from harm.
Seventy years later, members of the Equalists utilized chi blocking to combat benders during the Anti-bending Revolution. Amon, the leader of this underground organization, also frequently used the art of chi blocking.
While abducting members of the Triple Threat Triad, the Equalist organization was trailed and attacked by an angry Mako and Korra. In response, several of the chi blockers turned to fight them, disabling their bending, an action which frustrated and stunned Korra.
Amon carried a force of several chi blockers with him to a midnight duel with Korra on Air Temple Island. As the Avatar was walking away from the island, believing Amon was a no-show, she was ambushed by this force, who used chi blocking to prevent her from resisting her capture, allowing them to bring her before Amon.
Chi blocking is utilized by hitting pressure points with quick jabs and punches, and must be done rapidly, often giving little time for the recipient to react. Ty Lee hit those pressure points with relatively light jabs using her fingers and knuckles. Even people wearing strong, but not necessarily heavy, armor are not spared from its effects. Any fingers can be used, such as when Ty Lee disabled Katara with her thumb. Ty Lee could also use her feet to disable others' chi flow with a swing of her foot. She used this method to fend off the boys who cornered her in Chan's house.
Although a very useful method of fighting, chi blocking is most effective against an opponent not expecting such a light blow to be so devastating. It is less effective against someone who either knows chi blocking or who has battled a chi blocker in the past. An example of this was seen when Katara successfully dodged Ty Lee's attempts to block her chi after having already faced Ty Lee in an earlier battle. Additionally, chi blocking cannot work against an opponent wearing specialized armor like that of the Metalbending Police Force.
Later, when the Equalists demonstrated their ability at such techniques, it did not appear that their victims would become paralyzed like Ty Lee's did. Their blocks were powerful enough that they were able to force Korra and Mako onto the floor, but the two were able to move afterwards. This suggests that they could not perform the paralyzing technique that Ty Lee could, as it would have benefited them more to paralyze the two.
Chi blocking stops a bender's chi flow, reduces their muscular strength, and disables their bending abilities temporarily; this would be particularly devastating for people who rely solely on their bending to fight. Ty Lee had shown the ability to be able to control the damage done by such means: when she first attacked Katara with the art, she was still able to move, though not able to bend. In another instance, after assaulting the Terra Team, they could barely move, were powerless, and felt pain afterwards; Katara was unable to heal them, stating that their chi was completely blocked. Later, Ty Lee struck down Katara who was paralyzed from head to toe and fell to the ground motionless. However this attack could not have lasted very long, as Katara was later seen fully mobile.
Though nonbenders can also have their chi flow blocked, there are some differences in effect. Whereas chi blocking would temporarily stop a bender from bending, performing the act upon a nonbender in certain spots results in the loss of movement in that part of their body, as demonstrated when Ty Lee attacked Sokka. As he did not possess bending abilities, he instead lost voluntary muscular function within a region localized around the attack, essentially becoming paralyzed. This was a similar effect to Ty Lee's paralyzing blocks; except it occurred slower and he only appeared paralyzed in the places where she struck.
Azula described the chi blocking sensation as a feeling of all the joints going soft, "like they're made of melted wax", and one felt "more flexible than you ever thought possible" the moment the chi blocking effect wore off completely.
An accidental form of chi blocking was used twice against Combustion Man. On two occasions, his third eye was hit: once by a pellet resulting from Toph's attack, and once by Sokka's boomerang, deliberately aimed at him, causing him to "misfire". On the second occasion, the explosion was strong enough to demolish a section of the Western Air Temple, which led to his demise.
- Chi blocking resembles the martial arts technique, Dim Mak, which purports to kill or maim by disrupting the body's flow of internal energy.
- Qigong ( ) (sometimes spelled Chi Gung), a form of traditional Oriental medicine, uses similar techniques and pressure points to help others' chi flow more easily and is considered a standard medical technique in Chinese hospitals.
- Chi blocking also has some connections to Varma Kalai, an ancient martial art of Southern India.