Snakeriders of the Aradondo

From the back cover: Deep in the heart of a forgotten rainforest, a near-mythical race has been corrupted and labors to bring utter ruin and chaos in to the world.Somewhere in the Abyss, a demon lord waits with growing impatience for his unknowing minions to open that door wide. What obstacles await, you ask? Just a fetid river filled with giant crocodillians and enormous amphibians, hordes of savage simians and snakes the size of nightmares. Welcome to the Aradondo.