Specialized bending techniques

Within at least three out of the four bending styles, there exist more advanced moves that only a master can take advantage of. It takes either years of practice, or a bending prodigy to be able to manipulate outside of a certain move pool.

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. It was developed by Toph Bei Fong in the episode "The Guru". As of the end of the series, Toph remains the only known individual capable of Metalbending.

In the episode "The Guru", during a lecture on chakras, Guru Pathik explained to Aang that metal is merely earth that has been purified and refined. Using her unique ability to "see" through Earthbending, Toph is 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 a user to see things that may have been hidden or out of sight, such as in darkness (or in Toph's case, blindness). Only two known benders have been able to possess Seismic Sense: Toph Bei Fong and Avatar Aang.

Waterbending
Water is the most versatile of the four bending elements. It is able to become any of the three states of matter: liquid, solid, or gas. It also covers 75% of the earth's surface and is required for all life on the planet. Given these unique traits, there are several special abilities that a waterbending master can learn.

Bloodbending
Bloodbending is introduced in the episode "The Puppetmaster". 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/her internal organs or even completely extract the fluids from one's body imitating the technique used with plants, though this has not been stated. Bloodbending can only be performed at night during the full moon. Only two people, Katara and Hama, have been shown to have mastered this technique.

Steam Manipulation
A technique that allows waterbenders to manipulate steam. They can produce it from any water source. It can be used to freeze people or objects. It can also be used for cover. Katara made good use of the technique in "The Awakening" when she used steam to cover the ship for safety and in "The Painted Lady", when she surrounded herself in steam to create an eerie atmosphere. This may have been mist also, which is comprised of tiny water droplets suspended in air.

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. 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.

Lightning Generation


Lightning Generation is a sub-technique within Firebending, with which Firebenders are able to produce and direct a bolt of lightning from their fingertips. The generation of lightning was first shown by Princess Azula, during Book 2: Earth season premiere "The Avatar State", 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 (also an 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.

Lightning Redirection
Lightning Redirection is a sub-technique within 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.