The Green Hell (The Test of Time Supplement)
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The air smells foul on this plane, it is filled with the stench of stale water and putrid decay. The humidity, stench, heat eventually take there toll on everything and visitors have a hard time adapting to this alien environment, if they live long enough at all.
Gigantic swamp/rain forest, home to reptiles such as: Lizardman, Kobolds, Dragons, etc. Due to lots of sunshine and humidity the rate of decay on this plane is extreme, although it's hard to find sunshine here since the sun's rays are blocked off by the enormous vegetation and constant fog. Although "the green hell" is a wild and chaotic evil plane there is a sort of hierarchy, nobody crosses a dragon and so they are the only beings that could be considered leaders, there are of course tribes of Lizardman and such but they hold little to no respect for the other inhabitance of the plane. Finally there is the "vile" side of this plane, most of the inhabitants continually wages war on each other and there are a lot of beings that profit from the continual cycle of life, death and decay.
The greatest form of civilization on the plane is an enormous tribe of Lizardman that have constructed a great empire that stretches all across the great swamps in the south, this tribe (the black scales) has great numbers of druids and sorcerers and there knowledge of the ways of nature are unrivaled across the outer planes. But this focus of nature and magic is not the thing that made this tribe the largest on the plane; it was the constant warfare and total dedication of the warrior caste that conquered the swamps with tooth and club.
Visitors to the plane usually don't live long since it seems every inch of the world is inhabited by dangerous beings so caution is advised when traveling here. The only visitors that come to this plane come either to seek a powerful evil reptile (to worship, ask advice, seek power, etc.) or find magical items said to lay scattered through out the jungle and swamps of the plane. This is rare though because the corrosive and decaying air renders all but the most powerful items useless.
Meta-game description: "Vietnam" meets "Jurassic Park" meets "very sick horror movie", the result is a horrible jungle/swamp covert in nasty deadly animals and plants, topped off with a nice bit of poison mixed with natural magic.