Description from the front page of the adventure:
For years, the dungeons beneath Castle Greyhawk have been sealed but no longer. Crazed followers of the mad god have dissappeared inside, inviting the brave, the greedy, the pure, and the wicked to join them. Your invitation arrived this morning. Do you dare to follow them into the most infamous dungeon in all the Flanaess?
This Core Special was only available for play at GenCon 2004.
This is a special event for Living Greyhawk characters of any level. The event is divided into two parts, the low is for characters 8th level and lower, while the high is for 9th leveland up."