Tomb of Horrors is set in the World of Greyhawk, a D&D campaign setting. In Tomb of Horrors, the adventurers encounter a number of tricks and traps while attempting to penetrate the tomb of a dead wizard. As the scenario begins, the players are told that the evil wizard Acererak is said to linger in his ancient tomb in undead form. Originally a powerful lich, he has (unbeknownst to the players) become a demi-lich, a more powerful form of undead that has transcended the need for any physical body apart from its skull. Player characters must survive the deadly traps in the tomb and fight their way into the demi-lich’s elaborately concealed inner sanctum to destroy him once and for all.
The module is divided into thirty-three encounters, beginning with two false entrances to the tomb, and ending with “The Crypt of Acererak the Demi-Lich”. Example encounters are the “Huge Pit Filled with 200 Spikes” (section 20), or encounter 22, “The Cavern of Gold and Silver Mists”: “The mists are silvery and shot through with delicate streamers of golden color. Vision extends only 6′. There is a dim aura of good if detected for. Those who step into the mist must save versus poison or become idiots until they can breathe the clean air above ground under the warm sun.” The module ends with the destruction of Acererak, without any postscript. Most players have not finished the module successfully.
In RETURN TO THE TOMB OF HORRORS the nightmare of Acererak’s tomb once again hungers for life! Imagine a place of unspeakable evil. It was built upon hopelessness and filled with unending terror and pain. This loathsome place shattered the life of everyone who ventured near. But through tremendous sacrifice and heroism, over the course of many years, it was finally gutted and its foul creator destroyed. Now imagine that the horror is beginning all over again. The sinister wizard Acererak took great pains to safeguard his tomb. It took many years, and many more lives, before his evil was finally laid to rest. But though the demilich is gone, he is not forgotten. Others who would become as he was have traveled to the site of Acererak’s tomb seeking the secrets of mastery over death. Slowly these pilgrims gathered, eventually building in the shadow of the tomb itself a community dedicated to the dark arts: Skull City. But even these twisted necromancers have no inkling of the true evil that swells and crackles beneath their feet.
This module expanded significantly upon the plot of the original Tomb of Horrors, revealing that the tomb of the first adventure was merely an antechamber to the lich Acererak’s true resting place, and the demilich “slain” in the first adventure was both decoy and key to proceeding further. The dust from the destroyed skull opened a way to the cursed city of Moil in a pocket universe of eternal darkness and ice, and beyond that to Acererak’s fortress hovering at the edge of the Negative Energy Plane itself.
Acererak is revealed in this publication to be near the completion of a multi-thousand-year project to achieve godhood, powered by souls consumed over the years. He now needs only three additional souls to complete the process, but they must be of exceptional purity and strength; to this end he constructed his tomb to serve as an ultimate challenge for heroes, hoping to winnow out all but the very best. He would then consume them when they reached the center of his fortress, where his own undead essence resides in his phylactery. If the player characters fail to defeat Acererak in the course of the adventure they themselves could wind up serving in this role.