From the introduction:
The Emissary was originally designed back in the late 90’s as an adventure for 2e Dark Sun, intended to give players an introduction to some of the new locations being introduced south of the Tablelands - the Dead Lands.
Because the game mechanics for 2e gameplay are very different from 3.5e and subsequent editions, and also because over the decades since the Dungeons & Dragons community has learned more about adventure writing and player agency, this has made this adventure a deceptively difficult conversion.
While we have made a few changes throughout to ensure good pacing and appropriate challenge levels for the intended party level, all changes have been carefully considered in order to preserve the spirit and feel of the original adventure. The Emissary was and still is a 2e adventure partially converted to 3.0e, abandoned for over a decade, and then finally resurrected and converted to 3.5e for release. Some elements of this adventure will feel decidedly like “old school” Dark Sun, but the adventure has been tested and is quite playable and enjoyable in 3.5e even for those who aren’t a fan of those old style of adventures.