Specialized bending techniques

Within at least three of the four bending styles, there exist specialized bending techniques of which only a master can take advantage. It takes either years of practice or being a bending prodigy to be able to manipulate outside of a certain move pool.

Waterbending
Water is the most versatile of the four bending elements, for allowing any of the three states of matter: liquid, solid, or gas. Given these unique traits, there are several special abilities that a waterbending master can learn.

Bloodbending


Bloodbending was introduced by the Southern waterbender, Hama. Since the human body is roughly 70% water, bloodbending does not necessarily bend blood, but the fluids in one's body, allowing the user to manipulate a body's muscles to move as they wish or to stop movement completely. Potentially, a bloodbender could stop a victim's heart or crush his or her internal organs, pressurize, boil or cool the fluids, or even completely extract the fluids from one's body imitating the technique used with plants, though this has not been stated. Prior to Yakone's actions, bloodbending was thought to only be able to be performed at night during the full moon. There are only four known waterbenders that can perform this technique, being Hama, Katara, albeit reluctantly, Yakone, and his son, Tarrlok.

Plantbending


A member of the Foggy Swamp Tribe, Huu, has illustrated that talented waterbenders can manipulate plant life—from the highly water-saturated vines and roots found within the swamp lands and seaweed from the ocean floor—they can even rapidly regenerate the plant mass of the plants they bend, since the cell tissues of a plant is more versatile than the cell tissues of an animal, all by bending the ample amount of water within them just as they can with watery mud, as Hama demonstrated with fire lilies. Going further, a skilled waterbender is able to separate and completely extract the water from plants for more effective utilization just as they are able to separate the water from mud, sand, and even polluted river systems, etc. In the case of plant life, this process will then leave behind the withered remains of all the affected plant life or even making them collapse in the case of large trees.

Water Generation
As demonstrated by Hama, skilled waterbenders also possess the ability to gather water from their surroundings. Waterbenders are able to manipulate and acquire water from various sources including clouds, plants, living creatures, and the air itself.

Healing


Waterbenders also have the unique ability to heal themselves and others. They do this by drawing on the life-giving properties of water to heal many types of physical wounds, some illnesses, and even pain caused by mental stress. However, there are limits to what can be healed. For example, Katara's healing could not heal the internal injuries done to Jet by Long Feng, Yue's birth illness could not be cured by healers, and Zuko's scar would be unaffected by healing. It is also apparent that Katara cannot heal a bender whose chi has been blocked as shown when she was unable to heal the Terra Team. Water from the Spirit Oasis, however, has special properties and can heal wounds that regular water cannot, such as Aang's near fatal lightning wounds obtained during a duel with Azula. A healer can detect where chi flow is blocked, as displayed when Katara could feel the energy locked within Aang's chakra during a healing session. Avatars are also capable of this art, as Korra healed Bolin's shoulder following a pro-bending match.

Metalbending


Metalbending is a special subset of techniques within earthbending that allows an earthbender to ferrokinetically bend processed metals much as they would bend regular earth. The ability was discovered by Toph Beifong while she was confined in a metal box. At of the end of the Hundred Year War, Toph remained the only known individual capable of metalbending, though she ended up traveling the world to teach this skill.

During a lecture on chakras, Guru Pathik explained to Aang that metal is merely earth that has been purified and refined. Using her ability to "see" through earthbending, Toph was able to perceive the trace amount of earth still present in the metal, target it, and utilize it to bend the metal itself.

Seismic sense


Seismic sense is the ability to perceive objects' locations by feeling acute vibrations through the ground. Similar in application to sonar and echolocation, seismic sense enables the practitioner to visualize earth-based objects or objects in contact with earth-based objects when out of sight or, in Toph's case, unable to be seen due to blindness.

Only three human benders were known to have possessed seismic sense: Toph Beifong, Avatar Aang, and Lin Beifong. Badgermoles, the primal earthbenders, use seismic sense as an innate substitute for eyesight.

Sandbending
Sandbending is a form of earthbending where the particles of sand are manipulated. The sandbenders adapted the technique to survive within the Si Wong Desert. Most earthbenders would have an ability to bend sand, but because of the loose nature of sand and the similarity of the art to water and airbending, most earthbenders show an inability to adjust. Toph mastered sandbending, even to the point of nonchalantly creating a detailed model sand-sculpture of Ba Sing Se right down to a scaled version of the Earth King and Bosco.

Lightning generation


Lightning generation is a sub-technique of firebending, with which firebenders are able to produce and guide a bolt of lightning from their fingertips. The generation of lightning was first shown by Princess Azula while she was being overseen by Lo and Li. Generating lightning involves a circular motion with the arms. Mentally, it involves a complete absence of emotion and peace of mind, and physically it requires separating the energies of yin and yang, the spiritual interpretation of positive and negative electric charge. When the forces collide, the bender only guides, rather than controls, the lightning's direction. Because of this complexity, a lightning attack usually takes much longer to initiate than standard fire attacks, however Ozai was shown generating lightning very quickly when he attacked Zuko. Before the end of the Hundred Year War, only three firebenders were known to generate lighting; Azula, Ozai, and Iroh. However, the technique had become more widespread by the time Korra arrived at Republic City.

Lightning redirection


Lightning redirection is a sub-technique of firebending, allowing a firebender to absorb lightning into their body as energy, then release the lightning in a more desirable direction. The technique was developed by Iroh after he studied master waterbenders, who redirect force rather than oppose it head-on. Lightning redirection works equally well for natural and generated lightning. Iroh taught the technique to Zuko, who in turn taught it to Aang. Zuko redirected lightning multiple times in the series, as did Iroh. Aang only used this technique during his battle against Ozai.

Combustion


Combustion Man had a unique ability to channel his chi through his extremely overdeveloped third-eye mark in order to create a beam of energy by superheating the air around him. The beam explodes on contact, and is capable of great destruction, both in short and long range. Unlike normal firebending, this does not produce a flame directly from the body. Good chi flow and a properly calibrated focus around his third-eye mark is essential for this technique to be effective, as disrupting it can have fatal consequences for the user, as shown when Sokka hit his eye with a boomerang. Despite superheating the air, it does not appear to harm its user, unless the explosion occurs in the immediate vicinity. It can instantaneously evaporate large bodies of water with ease. It is possible to counter fire attacks, such as when Combustion Man stopped Zuko's fire shield during their brief duel at the Western Air Temple.

Cloudbending
A skilled waterbender or airbender can easily manipulate clouds, which are made of air and water, to create various shapes. In one particular instance, cloudshaping was used to provide a message to nearby villagers of an erupting volcano. It was later used as a defense by Aang and his friends to disguise their flights on Appa while moving about the Fire Nation. A waterbender can perform this technique without an airbender, as demonstrated when the invasion force used it for cover to approach the Fire Nation mainland unseen on Day of Black Sun, as well as by Korra when she manipulated steam.

Lavabending


There were not many displays of lavabending during the series, but it has been revealed that the technique is a combination of earthbending and firebending. This feat of power has only been displayed by Avatars. The first known user of this technique was the unnamed fire Avatar, who used it to make four volcanoes simultaneously erupt. Later, Avatars Kyoshi and Roku also utilized this technique to split Kyoshi peninsula from the mainland and to destroy the Fire Temple during the winter solstice, respectively.

Trivia

 * Airbending is the only bending art which as of the events of Avatar: The Last Airbender does not have a specialized bending technique.
 * Iroh and all of Team Avatar's benders displayed the ability to use multiple specialized techniques. Some of said skills included healing, bloodbending, metalbending, seismic sense, lightning generation, and lightning redirection.