Golden Trillium — Andre Norton

One of the famed triplet princesses who defeated the evil sorcerer Orogastus, Kadiya ventures forth into the choked swamplands of Ruwenda to seek her own destiny among the Oddlings she once led in battle. Armed with her mystical three-eyed sword, she reaches the lost city of the Vanished Ones and discovers a strange race of dream-catchers, called liassitti, whose visions bring chilling warning of a lethal plague that sows the land with death. Now Kadiya, with only three companions to aid her, journeys into the Thorny Hell, realm of the cannibalistic saurian Skritek, to stop the carrier of the evil disease. Here they discover a portal leading to a universe of awesome darkness--an entranceway to a horror that threatens the very existence of the World of the Three Moons.