A One-Round Living Greyhawk Bissel Regional Adventure
From the introduction:
"Convergences draws near, and with every feint and dodge of blade and arrow extinction draws near. The dead who walk are finished; they know not the truth. All that remains to be seen are all that remains after the death knell."
A Bissel regional adventure [character levels] 2 - 12, and Part 4 of the Shadows and Sigils series.