If you don't have it already, grab it now. Really. Right now. Not later, as you might forget. It's that good.
From the blurb:
In the days when man knew only the working of stone and fought for their existence against the orc and the goblin, the sky turned to ash and down fell the fiery mountain onto the land. The world tore open and the grey waters rushed in. Those who survived the impact were lost as boiling clouds rushed out in all directions leaving a wasteland in its wake.
The Mountain That Fell left a gift; magic. Near and far, those of learning and strong of heart discovered new powers to shape the world. In the desolation around the Smoking Bay the adventurous found viz, magic in physical form. And there was more, scattered amid the landscape were strange artifacts and stranger creatures that survived The Mountain That Fell. For a time men, dwarves, orc, goblins, and other races braved the dangers and fought each other in the wastelands. Then the elves came into Blackmarsh expelled the feuding races, drove the monsters out, and healed the land.
In the present day, many come to Blackmarsh to harvest viz, kill monsters, or seek the strange artifacts left by The Mountain That Fell. The only force that stands against the wilderness is the Blackmarsh Rangers. Anyone who is willing to defend the land and its people are welcomed into their ranks. Powerful kingdoms outside of Blackmarsh are beginning cast a covetous eyes toward the land's riches. Will the adventurers of your campaign become wealthy and powerful? Or will their bones join the many that have sunk into the swamps?
Blackmarsh is a complete, ready to run setting for your campaign. It can be run as its own setting or an expansion of your existing world. Contained in Blackmarsh are 17 geographical entries, 78 described locales, and one detailed town; Castle Blackmarsh. Each entry provide one or more adventure hooks to use in your campaigns.