The everful horn of a vengeful bull-like creature who wants it back…
It is a magical bug, that will allow the owner to hear what is said in the immediate vicinity of the “bug.”
This tome may give you the information you seek, though you may not be happy reading it. Not really cursed, but gives the information in such a way that many readers despaired before finding the right knowledge.
The extra-planar citadel of Ansern is named after its mage-founder. Ansern discovered the means to traverse the planar gulfs and created the citadel as a haven for his disciples in the art of planar-exploration. The disciples of Ansern continue his work and explore the countless worlds opened up to them by the work of the mage. They are cataloguing everything they discover in preparation for the greatest volume ever written: the Mondopedia, a book detailing many of the worlds. But the countlessness of the planes means that their book will never be finished.