The Death Gate Cycle Series by Margaret Weis, Tracy Hickman

Ages ago, sorcerers of unmatched power sundered a world into four realms--sky, stone, fire, and water--then vanished. Over time, magicians learned to work spells only in their own realms and forgot the others. Now only the few who have survived the Labyrinth and crossed the Death Gate know of the presence of all four realms--and even they have yet to unravel the mysteries of their severed world.. moreAges ago, sorcerers of unmatched power sundered a world into four realms--sky, stone, fire, and water--then vanished. Over time, magicians learned to work spells only in their own realms and forgot the others. Now only the few who have survived the Labyrinth and crossed the Death Gate know of the presence of all four realms--and even they have yet to unravel the mysteries of their severed world...In Arianus, Realm of Sky, humans, elves, and dwarves battle for control of precious water--traversing a world of airborne islands on currents of elven magic and the backs of mammoth dragons. But soon great magical forces will begin to rend the fabric of this delicate land. An assassin will be hired to kill a royal prince--by the king himself. A dwarf will challenge the beliefs of his people--and lead them in rebellion. And a sinister wizard will enact his plan to rule Arianus--a plan that may be felt far beyond the Realm of Sky and into the Death Gate itself. less

On steamy Pryan, never-ending sunlight and plentiful rain have created a jungle so vast that humans and elves dwell high in the trees and only dwarves live anywhere near the ground. From the treetops the aristocratic elves sell weapons to the other races, whose incessant warfare sends a steady steam of profits and essential resources skyward. Now, generations of dissent and race hatred will not heal -- not even under the threat of annihilation at the hands of legendary Titans... moreOn steamy Pryan, never-ending sunlight and plentiful rain have created a jungle so vast that humans and elves dwell high in the trees and only dwarves live anywhere near the ground. From the treetops the aristocratic elves sell weapons to the other races, whose incessant warfare sends a steady steam of profits and essential resources skyward. Now, generations of dissent and race hatred will not heal -- not even under the threat of annihilation at the hands of legendary Titans. Armed with little more than their wits and prophecy, an elf, a human, and a dwarf must unite to try to save the world from destruction. less

Abarrach, the Realm of stone. Here, on a barren world of underground caverns built around a core of molten lava, the lesser races -- humans, elves, and dwarves -- seem to have all died off. Here, too, what may well be the last remnants of the once powerful Sartan still struggle to survive. For Haplo and Alfred -- enemies by heritage, traveling companions by necessity -- Abarrach may reveal more than either dares to discover about the history of Sartan... and the future of all their descendants."

In the fourth volume of this epic fantasy, Haplo must outwit lethal and magical serpents in the last of the Four Realms.

Chaos is everywhere as the Lord of the Nexus orders his servant Haplo and the human child known as Bane to further their master's work on Arianus, the realm of air. But their one time companion Alfred has been cast into the deadly Labyrinth. And somehow the assassin Hugh the Hand has been resurrected to complete his dark mission. More important, the evil force that Haplo and Alfred discovered on Arianus has escaped... moreChaos is everywhere as the Lord of the Nexus orders his servant Haplo and the human child known as Bane to further their master's work on Arianus, the realm of air. But their one time companion Alfred has been cast into the deadly Labyrinth. And somehow the assassin Hugh the Hand has been resurrected to complete his dark mission. More important, the evil force that Haplo and Alfred discovered on Arianus has escaped. As Haplo's doubts about his master grow deeper, he must decide whether to obey the Lord of the Nexus or betray the powerful Patryn...and endeavor to bring peace to the universe. less

Haplo, targeted for death by two assassins, and Alfred enter the terrifying Labyrinth, a prison maze guarded by fearsome creatures. Meanwhile, the Lord of the Nexus raises an army from the dead to attack the Tytans.

The Seventh Gate is the thrilling conclusion to the New York Times bestselling Death Gate Cycle by Margaret Weis and Tracy Hickman. In this tale of treachery, power, and heroism, Alfred, Haplo, and Marit embark on a journey of death and discovery as they seek to enter the dreaded Seventh Gate. Encountering enemies both old and new, they unleash a magic no power can control, damning themselves to an apocalypse of unimagined proportion in a final struggle between good and evil.