A river of words flowed between us.
Acererak was a powerful wizard who became a lich, and later a demilich. He appears in the original Tomb of Horrors adventure by Gary Gygax as the main adversary, and later as the guardian of the Copper Key, during the quest for Halliday's Egg.
Acererak first appears in the original Tomb of Horrors adventure (1978) by Gary Gygax as the main adversary. One of the areas in the Tomb is a "Chapel of Evil", described as "obviously some form of temple area - there are scenes of normal life painted on the walls, but the people have rotting flesh, skeletal hands, worms eating them, etc." He also has rubies for eyes.
The adventure described him as "a human magic-user/cleric of surpassing evil" who took the steps necessary to preserve his life force as the lich, Acererak."
Acererak guards the Copper Key in a digital recreation of the Tomb of Horrors. If an OASIS avatar approaches him after completing the rest of the Tomb, they will be challenged to a match of Joust; should the player defeat Acerak in a best-of-three set, they will obtain the Copper Key. If the player loses, their avatar will be forced to fight Acererak.