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 is a specialized technique within the art of waterbending that allows a waterbender to hydrokinetically take hold of the various fluids contained within a living organism's body and then manipulate them to control the movement of their intended target. The technique is revered as the darkest and deadliest sub-skill of any of the bending arts.
The forms and styles used by bloodbenders are very similar to how a puppeteer controls a marionette, in particular the hand shape and movements. Whereas waterbending uses flowing motions with the arms, bloodbending seems to require a more rigid and abrupt form of movement, further highlighting how different it is from the primary waterbending forms and its other sub-skill, healing.
Due to its extreme nature, only a handful of waterbenders have demonstrated the ability to bloodbend. The technique is deemed by most waterbenders to be a dark art and is rarely used in combat. The complexity and sophistication required to perform the art usually only allows for its use during a full moon, when a waterbender's power is at its absolute peak.
Bloodbending is infrequently applied to daily activities. Knowledge of the art eventually became known to the public, and the practice of bloodbending was outlawed.
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. 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.
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. A healer can detect where chi flow is blocked. Any skilled waterbender can perform this art.
Metalbending is a specialized sub-skill of earthbending that allows an earthbender to ferrokinetically bend processed metal in a similar fashion to bending regular earth. The technique was invented by Toph Beifong after Xin Fu and Master Yu captured and transported her in a metal cage, which she metalbent and subsequently escaped.
Seismic sense is a sub-skill of earthbending that constitutes for physical sense. This skill enables earthbenders to detect vibrations in the ground to perceive objects, people, and other aspects of their environment, essentially acting as sonar, but through the earth.
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.
Lightning generation is a sub-technique within firebending where firebenders are able to produce and direct a bolt of lightning from their fingertips.
The art was almost entirely exclusive to the Fire Nation Royal Family prior to the start of its use in Republic City's industrial district.
Physically, generating lightning involves a circular motion with the arms. Mentally, it involves a complete absence of emotion and peace of mind, thus allowing you to separate the energies of yin and yang, the spiritual interpretation of positive and negative electric charge, within you. 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.
Lightning redirection is a specialized technique within the art of firebending that allows a firebender to absorb lightning into their body as energy, then release it in a more desirable direction. The technique was developed by Iroh after he studied master waterbenders, who redirect an opponent's energy rather than oppose it head-on. Lightning redirection has been shown to work equally well for both natural and generated lightning, as well as electricity conducted through metal.
Redirecting lightning deals with the flow of energy in a firebender's body and turning an opponent's energy against them, a technique waterbenders use in battle. The person redirecting it must create a pathway from fingertips, up the arm to the stomach, then up and out the other arm. The stomach is referred to as "the sea of chi", as it is the source of energy in the body. It is essential that the lightning pass through the stomach, as if the lightning passes through the heart, the effects could be fatal. A physical motion may help focus the energy flow in the path through the body.
Lightning can be successfully redirected regardless of whether the source is natural or generated lightning. It can also be redirected through an intermediate electrified cord.