Fathomless Pits of Ill Intent

From the introduction: The time is now! The yuan-ti lay on the cusp of freeing an ancient being of insurmountable evil from its imprisonment. Should this happen, Faerûn may very well be plunged into an age of darkness. You have traveled with width and breadth of the peninsula and learned what you could about your foe. Now it’s time to put that knowledge to use. Steel yourself, adventurer, there are important deeds to be done!