Kwai was a magician who was exiled to the North Korean Nome for killing a fellow magician.
Carter described him as an Asian man wearing a blue robe. He is one of the magicians commanded by Vladimir Menshikov to attack the Brooklyn House. He is later seen fighting the magicians from the Brooklyn House.
In The Serpent's Shadow, Kwai and Sarah Jacobi worked to bring down the Kanes and the House of Life. Kwai fought Amos Kane in the Hall of Ages, using red lightning to bring down Amos' Set avatar, and was possessed by Apophis briefly after the death of Jacobi. He was defeated by Walt Stone and Anubis' jackal warriors and used all of his remaining life-force to cast a spell to bring down the Hall of Ages in an attempt to win even after dying. However, Sadie manages to defeat his plans by casting Ma'at.
Not much is known about Kwai's physical appearance, except that he is Asian, has no hair, and that he usually wears blue robes.
Kwai studied Chaos and storm magic, more specifically working with lightning. Leonid, a Russian magician, says Kwai does terrible things with lightning as a punishment. When possessed by Apophis the Chaos Serpent, Kwai became extremely powerful, able to easily fend off Carter (the host of Horus), with incredibly increased red lightning abilities. It took the combined effort of four gods to successfully overpower him, and even then he had enough energy to bring down the Hall of Ages. Also, while battling Amos Kane (the host of Set), Kwai displayed the ability to defy gravity.