Quest-critical crystal holding secrets about Emberus's dead son, now in Prepotente's hands and coveted by the Epicure.
Carl's quest from Emberus, Find Out Who Killed My Son, updates in the ruins of Larracos: the Memorial Crystal: Apito has fallen from Osvaldo's hands and is now in the possession of Prepotente. Carl must retrieve it from him before the goat cracks its secrets and gives them to The Epicure.
Carl has no idea how the crystal changed hands without a fight, and resolves to sit down with Prepotente later and explain everything — suspecting the goat will be an ass about it, and wanting to do it when neither of them is so keyed up. Notably, Emberus says nothing at all about Carl's conversation with Eris, which Carl had been bracing for.
A memorial crystal bearing sealed secrets about the god's dead son.
The object of Emberus's quest, whose secrets must not reach the Epicure.
Also appears in books you've already read — spoiler-safe to their endings: