Energybending

Energybending is a unique skill, not bound by elemental attachment. It allows the user to manipulate the energy within another person. For successful energy bending, the user's spirit must be unbendable.

Learning Energybending
Canonically, only Avatar Aang and Avatar Korra are the only people to have used Energybending, hence suggesting that only Avatars can learn it. Despite this, Lion Turtles have been shown as teachers of Energybending, and so it could also be suggested that anyone can learn Energybending.

Our knowledge of the war is limited in detail, but we know from Wan's time to when Aang met the Lion Turtle, they were hunted to just one. This does not limit there being more than one at the start of the Hundred Year War, but the numbers should be within reason; hence, the odds of coming across a Lion Turtle to teach Energybending.

Removing bending
The bendability of the player's spirit is determined by the simple equation: (Intelligence + Wisdom) ÷ 2. This gives a maximum value of 20 (extremely sturdy) and a minimum of 1 (extremely bendable). If the player and the opponent have the same bendability (which can be determined by the equation or 5d4), the DM and player both roll a d20. The higher number wins.

If the player's value is higher, then the opponent will lose their bending and be stunned for a turn. The player will also be stunned for a turn.

If the player's value is lower, they may roll a d20 to decide their fate. In order to avoid corruption and hence loss of bending, they must roll thirteen or above, twice. Should they succeed, they will break out of the energybending and have their chi halved. Should they fail, they will lose their bending. The severity of their corruption is now decided by another d20 roll. Should they crit. fail (1), they will be destroyed: no body, no trace. These rules clearly establish that energybending should not be taken lightly as the punishments for its failure are most severe; however, for most players this should be a null issue, as coming across a teacher for energybending (e.g. a lion turtle) is neigh impossible.

Astral Projection
"Tapping into the vast expanse of cosmic energy, the bender is able to bend the energy within themselves to create an astral projection of their spirit. The projection can sustain damage, deal damage, bend, and fire a special beam of light."

Astral form
For a character to be able to do astral projection, the must have a very strong connection to the cosmic energy. This can be achieved in a few ways: When in astral form, the character's gains the following properties:
 * Being near a source of cosmic energy/a sacred location (e.g. the pond in the Northern Water Tribe; the Banyan-grove tree)
 * Meditating with complete serenity
 * Wielding certain items with a strong spiritual connection (e.g. meditation beads; Kyoshi's Dress)