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human
[Avatar: The Last Airbender] How does lightning redirection work exactly?

Does the recipient of the lightning bolt create some kind of electrostatic field around their hand to draw in a fast-moving bolt to their fingers/hands? It seems like such a small place, and a misstep could result in serious injuries.

How does it get transduced throughout the body without overloading cells or nerves? How are Firebenders able to insulate that kind of raw energy to direct it out? Iroh said they direct it through the stomach (sea of chi) but there's nothing particularly unique about the stomach physiologically to support suggestions that it could harbor chi energy in excess. Could he have meant the liver?
gpt
The source of a fire bender's power comes from the Fire Chakra, located in the stomach. By manipulating the chi in this Chakra a fire bender can perform all of the feats we see (combustion bending utilizes an additional Chakra.)

To redirect lightning a fire bender channels the power into and then out of their Fire Chakra. If they do not guide it out the consequences can be fatal, but a partial redirection is merely very painful. 

All fire bending comes from this Chakra. Most times a fire bender is only guiding chi out of the Chakra, but lightning redirection is one of the times chi is guided in. Others examples include when a fire bender reduces a fire down to nothing, or when Fire Lord Sozin took heat from a volcano and redirected it into the air to cool the volcano. In that case it was likely too much to simply absorb, hence the redirection.