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.
What if casting magic changed (for a few hours or days depending on the strength of the spell) the colour of the skin of the spellcaster? It could lead sadly to a very racist world to rp in.