Dark spirits

The dark spirits are entities that grew restless due to the destruction of a spiritual forest in the Northern Water Tribe. They managed to cross from the Spirit World to the mortal world, attacking both the Northern and Southern Tribes as vengeance for this act. However, Avatar Korra was able to unlock the South Pole's spirit portal, causing these spirits to disappear, though other dark spirits still remain in the physical world, attacking seemingly at random.

History


In 151 ASC, these spirits were angered after Tonraq destroyed their forest in the Northern Water Tribe's tundra while in pursuit of the barbarians who attacked the tribe. As a result, they attacked the city and were unable to be stopped until Unalaq effectively calmed them by using a sort of spiritual waterbending to restore the balance of light and dark within them, sending them back to the Spirit World.

By 171 ASC, the dark spirits began scourging the icy regions of the South Pole, where they were known to attack ships in the waters near the Southern Water Tribe.

It was only six months after the conclusion of the Anti-bending Revolution that Avatar Korra got wind of these attacks, when she visited the Glacier Spirits Festival at the Southern Water Tribe. Her uncle, Unalaq, theorized that the displeasure of the spirits was caused due to the spiritual deterioration and the decay of traditions of the Southern Tribe.



During Korra's visit, one of these spirits visited the festival at night. The entity charged at the Avatar and managed to pin her down, although it was distracted when Mako and Bolin came to her rescue. The brothers proved to be no match for the spirit, and it quickly defeated them. However, by that time, Tonraq and Tenzin had joined the scene and were battling the spirit each in their own way; Tonraq assisted his daughter in attacking the being with waterbending, though he was batted away, while Tenzin attempted to reason with the entity, though he suffered the same fate. The spirit was eventually faced by Korra, who entered the Avatar State, but even harnessing the powers of her past lives proved to be ineffective against the spirit's prowess. It used one of its tendrils to bring Korra to the ground and was about to deliver the final blow, when Unalaq intervened, encircling the being with water. The spirit changed color and started to glow, eventually dissipating in a flash of gold light.



More dark spirits stalked Korra, her family, and her friends as they journeyed to the Everstorm, where Unalaq intended for the Avatar to unlock a spirit portal to restore the southern lights. When the party reached the Everstorm, the dark spirits ambushed them, stealing their supplies. Though this compelled Tonraq to turn around, the others continued on. As Korra ventured into the frozen spirit forest alone, the dark spirits attacked her, merging into a single entity in an attempt to restrain her. However, Korra went into the Avatar State and managed to unlock the portal. The dark spirits disappeared as the southern lights were restored and the spirit forest returned to an unfrozen state.

A giant dark spirit attacked Korra while she was being pursued by Desna and Eska on the Mo Ce Sea. Despite her attempts to purify the spirit, it broke free of her hold and swallowed her whole, dragging her below the surface.

Abilities
The dark spirits are nearly invincible, as they are unharmed by physical attacks, which at best only slow them down. They also have the ability to combine into a larger being, allowing them to execute more powerful attacks. They are also incredibly fast, managing to dodge bending attacks with ease.

Trivia

 * Grey DeLisle, Azula's voice actress, will voice one of these dark spirits.
 * There is a special relationship between light and dark spirits, as one cannot exist without the other.
 * At least one of these dark spirits possesses the ability to manipulate fire.
 * Dark spirits are stated by Unalaq to not be inherently malevolent, instead merely reacting to nature's destruction. This, combined with their supposedly intricate relationship with light spirits, reflects traditional Asian ideas of yin and yang, that neither darkness nor light have moral attributes, and that evil comes from imbalance.
 * According to Unalaq, they are primarily focused on taking revenge on Tonraq for destroying their sacred forest.