Dweomerheart is a fictional geographic location in the fantasy setting of the Forgotten Realms.
Dweomerheart is the fortress of the Goddess of Magic, Mystra, located in the realm of Nirvana. The fortress is described in only a few of the Forgotten Realms books, including The Avatar Series. The Avatar Series details the Time of Troubles in Faerûn. Dweomerheart is described in Prince of Lies by James Lowder, the fourth book in The Avatar Series, in which Mystra kidnaps Cyric's inquisitors in an attempt to turn them against him. In the center of the realm of Nirvana is Mystra's fortress of pure magic, which is described in detail. When Mystra brings the inquisitors inside, Gwydion the Quick describes the scene about him:
...the Lady of Mysteries stood in the courtyard of her heavenly palace. The castle and walls protecting it were drawn from the magical weave, pulsing blue-white radiance that flickered like faerie fire in a midnight marsh. Bright pennons snapped and fluttered from an infinite number of tall spires. Each flag bore the sigil of a wizard or sage granted a home in Mystra's realm. In their towers lay workshops, wonderfully strange and arcane places where the faithful freely pursued the more elusive secrets of sorcery denied them by the limits of mortal life.—Gwydion the Inquisitor in Prince of Lies
She welcomes the inquisitors into the courtyard of Dweomerheart, which is described as being populated by the souls of the followers of Mystra, and every mythical beast ever documented, as well as some that aren't. The creatures seem to have lost all of their mortal tendencies, intermingling with each other and Mystra's worshipers freely:
Dragons of silver and gold perched on the high battlements and unicorns wandered over the lush, verdant lawn. Other creatures of magic called the palace home, as well. basilisk and cockatrices roamed the gardens, their eyes masked by special enchantments to prevent them from turning the unwary to stone. A ram-headed sphinx perched near the front gate, exchanging riddles with a couatl. The feathered serpent laughed at some jest and beat the air with its alabaster wings.—Gwydion the Inquisitor in Prince of Lies