A Three-Round Adventure set in the World of Greyhawk
From the introduction:
Before there was the Circle of Eight, before even the Citadel of Eight, Mordenkainen saw the need for a personal group of heroes to help maintain the balance in Oerth. See how the Citadel of Eight formed in this daring adventure.
This adventure is background for the Living Greyhawk campaign.
An adventure for characters levels 7-8, characters provided.
This adventure was distributed as two separate PDF files: a 49-page PDF scenario and a 13-page PDF print-and-play component (player handouts). The item code of COR1-00 is unofficial, but universally utilized.