The Death Gate Cycle

The Death Gate Cycle is a seven-part series (heptalogy) of fantasy novels written by Margaret Weis and Tracy Hickman. The main conflict is between two powerful races, the Sartan and the Patryns, which branched off from humans following a nuclear/anti-matter holocaust. Centuries prior to the events of the series, the Sartan attempted to end the conflict by sundering the Earth into four elemental realms, and imprisoning the Patryns in a fifth prison world, the Labyrinth. The Sartan took up stewardship of the elemental realms, but soon mysteriously lost contact with each other and disappeared. Centuries later, a Patryn known as Xar escaped the Labyrinth, and started returning to the Labyrinth to rescue others. He learned how to access the other worlds and dreamed of freeing all his people from the Labyrinth and conquering the other worlds. The books follow the fiercely independent Haplo, a Patryn agent sent to scout the elemental worlds and throw them into chaos in preparation for his Lord's conquest of them. Weis and Hickman created five distinct fantasy worlds during the course of the series, along with developing the cultures of five major races: the unique Patryn and Sartan, and the common fantasy races of dwarves, elves, and humans.

Margaret Weis and Tracy Hickman had finished their Dragonlance and Darksword series prior to The Death Gate Cycle, which may be considered their most ambitious work yet, as they created multiple fully realized and distinct worlds. The series also displayed Weis and Hickman's continued command of the fantasy genre.

As in their previous works, the authors continued to explore the theme of balance, and how the universe naturally works to correct imbalances.

Unlike in Dragonlance, where the universe's balance was a greater force than even the gods, the existence of a god or gods in The Death Gate Cycle is unknown; a universal balance is the closest thing to divinity. Along a similar line, the authors continued to explore the theme of men becoming gods—in this case with the entire Patryn and Sartan races clamoring for that throne. Finally, as in both Dragonlance and the Darksword series, they explored the effects of sweeping changes to the fundamental nature of a world (in this case worlds) on both the day-to-day life and the fate of nations.

...
Wikipedia