Silvern (Gilded #2) by Christina L. Farley
Jae Hwa Lee has destroyed Haemosu, the dangerous demi-god that held her ancestors captive, and now she’s ready to forget about immortals and move on with her life. Then the god of darkness, Kud, sends an assassin to kill her. Jae escapes with the knowledge that Kud is seeking the lost White Tiger Orb, and joins the Guardians of Shinshi to seek out the orb before Kud can find it.
But Kud is stronger and more devious than Haemosu ever was. Jae is soon painfully reminded that by making an enemy of Kud, she has placed her closest friends in danger, and must decide how much she can bear to sacrifice to defeat one of the most powerful immortals in all of Korea.