Specialized bending techniques

Within three of the four bending styles, there exist specialized bending techniques of which only a skilled bender can take advantage. Depending on the specialized bending skill, different levels of mastery are required 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. However, until the time of Yakone, bloodbending was only thought to be achievable during the full moon.

In 128 ASC, a man named Yakone demonstrated the ability to bloodbend without a full moon. Furthermore, Yakone was able to bloodbend his victims with his mind, a technique known as psychic bloodbending, which allowed him to bloodbend people without moving his hands. Later in life, Yakone taught his two sons, Noatak and Tarrlok, how to bloodbend without a full moon. By the age of fourteen, Noatak had mastered his father's psychic bloodbending technique. Also, an extremely powerful and gifted bloodbender can take bending away; Amon used this power to carry out the Anti-bending Revolution.

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 are 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, polluted river systems, etc. This process will then leave behind the withered remains of all the affected plant life or, in the case of large trees, cause them to collapse.

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. Moreover, healing cannot restore bending after it has been severed by Amon's unique form of bloodbending, even if the healer herself is a master and capable of bloodbending, as shown by Katara at the South Pole. Water from the Spirit Oasis, however, has special properties and can heal wounds that regular water cannot, such as Aang's 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. Any skilled waterbender can perform this art.

Metalbending


Metalbending is a special subset of techniques within earthbending which allows an earthbender to indirectly bend processed metals by bending the trace amounts of regular earth in them, much as they would bend regular earth. The ability was discovered by Toph Beifong while she was confined in a metal box. After the Hundred Year War, Toph remained the only known individual capable of metalbending, though she ended up traveling the world and starting her own school to teach this skill. The years following this led to the establishment of Republic City's Metalbending Police Force, whose members, as their name states, enforce the city's laws by use of the technique to arrest lawbreakers.

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. However, when the metal is pure enough, such as platinum, it cannot be bent.

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. Physically, generating lightning involves a circular motion with the arms. Mentally, it involves a complete absence of emotion and peace of mind, thus allowing one to separate the energies of yin and yang, the spiritual interpretation of positive and negative electric charge, within one. When the forces collide, the bender 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; however Aang only used this technique during his battle against Ozai. Apparently, knowledge of this move spread well throughout Republic City. Also, this move was shown redirecting the electricity of an electric grapple of a Mecha tank.

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, and has the capability 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.

Mudbending
It has been demonstrated that both earthbenders and waterbenders can bend mud, due to the substance's water and earth content. Katara halted the flow of the slurry in the back of the drill to prevent Ty Lee from following her. Later on with Toph's aid, they were able to push the slurry back further into the drill. Katara and Toph also used this against each other when they ended up fighting when they were supposed to be training Aang.

Trivia

 * Airbending is the only bending art which as of the events of Avatar: The Last Airbender does not have its own specialized bending technique.
 * Iroh and all of Team Avatar's benders displayed the ability to use multiple specialized techniques. Some of these said skills included healing, bloodbending, metalbending, seismic sense, lightning generation, and lightning redirection.
 * In all known specialized bending techniques which can be performed through the manipulation of more than one element, the elements involved are never opposites. Of all possible non-opposite combinations, only air/fire lacks a technique which can be performed by a bender of either element.