A One-Round Living Greyhawk Bissel Regional Adventure
From the introduction:
"Convergence arrives, mark it with the death of the oasis who walks. Extinction draws close; the agenda of the spheres is righted at end. All memory fades of the ones who walk and move into the dark lands."
A Bissel regional adventure for [character levels] 2-12, and finale of the Shadows and Sigils series.