Tui's death lead to a lapse in spiritual balance, and waterbending ceased to exist. Yue sacrificed her life in order to save the Moon Spirit. Zhao appeared to heed Iroh's warning, releasing Tui back into the water of the Oasis, but the spirit was then abruptly murdered by Zhao with a blast of firebending, much to the horror of Katara, Aang, and Iroh.

General Iroh intervened and threatened Zhao that any harm inflicted on the spirit would be unleashed on him tenfold. Tui was captured by Zhao, causing the spiritual equivalent of a lunar eclipse and removing the power of all waterbenders. Determined to make a legend of himself, Zhao lead his personal guard into the royal palace to kill the Moon Spirit, whose mortal existence he had learned from Wan Shi Tong's Library. Many years later, Admiral Zhao launched a massive attack on the Northern Water Tribe on behalf of the Fire Nation. Although Tui had saved Yue, Chief Arnook had a dream that his daughter would one day have to share Tui's place as the Moon Spirit. Tui answered their prayers and saved the princess by passing on some of its own life force. When Princess Yue was born, she was gravely ill and on the brink of death, so her father, Chief Arnook, and mother brought her to the Spirit Oasis and prayed for the spirits to save her life.

Thereafter, the Spirit Oasis became the city's most treasured landmark. They lived within this spiritual center of the North Pole and took the form of two koi fish. Reportedly 'near the beginning of time', Tui and La chose to manifest themselves in the mortal world to benefit mankind and took up residence in an alcove within Agna Qel'a.

Yin and yang symbol avatar the last airbender