From the introduction:
A Two-Round Living Greyhawk DM's Challenges High-Level Option Adventure Packet for 16th- to 20th-Level Characters
Living Greyhawk DM's Challenge 4
For the Horrors Never Die Story Arc (2006 - 2007)
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[With a DM's Challenge adventure packet] you get basic guidelines, a special session tracking, and a basic Adventure Record (AR) for an adventure that you write or modify and run.
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The Horrors Never Die Story Arc (2006-2007) deals with the awakening of yet another danger to Oerth at the Tomb of Horrors, one of the Flanaess’ most fabled locales.
The arc consists of four adventures, three of which are DM's Challenge adventure packets and one of which is a fully written adventure.
The Horrors Never Die Story Arc (2006-2007) is:
DM's Challenge 1
DM's Challenge 2
Return to the Tomb
DM's Challenge 4