Kent Nelson visited Xanadu's store, and requested that she make contact with his deceased wife, Inza. During the seance, wind blew around the room and the table appeared to levitate, and Madame Xanadu appeared to channel Inza, saying that she was cold and lonely. However, this show only led to Kent bursting into laughter. Despite her attempts to maintain the illusion and keep the money saying that there were no refunds for non-believers, Kent easily exposed her as a fraud: she used wind machines and tire jacks to make her performance look convincing. He was disappointed at not being able to speak with his wife, and also at the fact that Madame Xanadu was pulling a scam, when in fact she has the right aura for real magic and psychic abilities.
When Madame Xanadu witnessed Abra Kadabra kidnap Kent Nelson and perform apparently real magic in order to make them disappear into thin air, she ran away screaming.
Following her encounter with Kent Nelson and Abra Kadabra, Madame Xanadu was inspired to unlock her hidden dormant powers and in time became the greatest seer and medium on Earth. At some point, she also became friends with Zatanna.
Zatanna and her students visited Madame Xanadu from the Harlem entrance to her parlor. After some introductions were made, Zatanna and Xanadu discussed the wave of chaos energy they had both sensed. Xanadu did not know the cause, but was able to locate a recent position of its source. Xanadu opened a portal there, but reminded Zatanna to pay her fee before leaving. She also offered a parting warning about the power of what she had sensed.
Nimue spent months trying to locate Superboy's spirit for Zatanna, leading her to the Bayou to cast a spell. Though she saw many souls reflected in the water, she did not find who she was looking for, and called Zatanna with the bad news.
In DC Comics, Madame Xanadu is a powerful immortal character who is supernaturally sensitive and able to properly foresee the future using Tarot Cards, as well as cast spells, and is actually Nimue from the Arthurian mythos. Madame Xanadu is currently a member of Justice League Dark.