story identification - Fantasy book series with non-human races and labyrinth

I'm trying to identify fantasy book series I encountered some time ago. Here are things I remember:

• it was a fantasy setting but with some s-f elements; with many worlds and possibility to travel between them; resembling Planescape setting a little,


• the two main races were non-human and probably hostile to each other,


• a labyrinth (?), which somehow played an important role in the plot,


• a protagonist was some kind of emissary and was sent on a mission to another worlds


• time period: 80s - 90s

Does anyone know what it is the name of the series?

Answer

The Death Gate Cycle is a series of seven fantasy novels by Margaret Weis and Tracy Hickman that involves planar travel and contains quite a few sci-elements. The books were released between 1990 and 1994.

The series features:

• Travel between multiple elemental planes of existence: the Plane of Fire, Plane of Earth, Plane of Air, Plane of Water.


• The the Sartan and the Patryns, two godlike races, are locked in a war to control the other, "lesser" races (Dwarves, elves and humans).


• The Labyrinth is a prison world that figures largely into the Sartan/Patryn conflict. Spoiler alert:
  

  
  

  The Patryn are imprisoned there.

  
  

  
  
  


• One of the main characters is Haplo, a agent of the Patryn who travels among the Elemental worlds at his master's request.