The Tomb of Horrors is where the demilich Acererak lived and used his magic to manipulate the elves into his service. He obtained the Eye of Vecna and was attempting to get the Hand of Vecna as well as the Orb of Light in order to create an unstoppable army of undead.
The Tomb of Horrors is notable for its exceptional traps and near emptiness. The only monsters in the tomb are asps, gargoyles, a mummy, and Acererak. The Tomb is located under a black stone hill. On top of the hill lay ancient ruins, which the adventurers ejaculated upon. After venturing inside, the party had to overcome many puzzles and traps. They were fortunate to have riding lizards with ghost bridals, with which they could become insubstantial. The party eventually acquired a gem which could grant wishes. Unbeknownst to them, however, the gem was cursed, and each wish it granted would be harmful to the wisher. The party wished that they would be brought to the Eye of Vecna. They were then teleported to the room the Eye was in, but were flung against the wall, sustaining injuries in the process. After defeating Acererak and obtaining the Eye of Vecna, the adventurers gave the Hand and the Eye over to the Mages' Guild of Glidden .
During the course of Rise of the New God, the adventuring party Pronefest explored three of Acererak's new tombs, as well as the original Tomb of Horrors.
The Garden of GravesEdit
Deep within the forests of the Feywild the heroes discovered a desecrated Eladrin graveyard which Acererak had converted into a planar engine to shunt the magical essence of the plane to power his phylactery. Here the heroes first discovered the planar crossover between the tombs and received their first planar visions of the other tombs; though they were unable to put together the clues at the moment.
The Shadow TombEdit
Hidden far within the dark reaches of Moil the heroes found Acererak's second tomb. The planar engine here was protected by a series of life-draining traps which nearly brought the adventure to an end. It was during the final confrontation in this tomb that Ki-amar went mad and threw himself into a portal containing the pure essence of the Shadowfell, thus allowing Acererak to claim his soul.
The Abandoned TombEdit
The original Tomb of Horrors underneath Skull City was discovered by Pronefest during the events of Rise of the New God. The upper part of the tomb was found to be largely empty of monsters, with most of the traps already activated or destroyed, and to have been drained of all magic. Deeper within the tomb Bûrzum Rung-Pilik and Krusk were dominated by an eladrin woman, and forced to kill Mindartis. After defeating her, Pronefest raised Mindartis from the dead and the eladrin adventurer took a brief retirement from the adventuring lifestyle; during which time Pronefest found a new companion in the pixie, Syraphina Tealeaf.
Hidden under the main tomb Pronefest discovered Moghadam, the foul architect of the crypt who went mad and now desired to kill Acererak. In a challenging battle Pronefest slew the wraith and Bûrzum claimed his sentient greatsword, Ruinblade, which desires the final end of Acererak.
The Dead Gods' TombEdit
Acererak's final tomb was secreted away on the astral domain of Pluton beneath Nerull's former palace, Necromanteon. Here the demilich had linked the palace to shrines devoted to the other dead deities and had warded them with potent traps. The party fought valiantly through the tomb, and although Ildirin Suvarmaq and Mindartis briefly died, they were victorious in destroying Acererak's god-golem and phylactery, thus ending his hope of becoming a god.