Two unrelated “court tales” such as the mission of bishop Marutha to Yazdgerd I in the Ecclesiastical history by the Greek historian Socrates (5th c. CE), and the account of the Zoroastrian heretic Mazdak preserved in the Siyāsatnāma by the Seljuk vizier Niẓām al-Mulk (11th c.), share a common narrative: an impostor contrives to make the sacred fire speak, but is ultimately exposed. By tracing this literary motif back to the prophetic biography of Zarathustra, this paper explores how the theme was transmitted, enriched, and re-functionalized, through the lens of the Book of Daniel, in various Eurasian traditions: through this exemplar case study we point out the prospects and challenges involved when researching the karstic emergence of ancient Iranian patterns across different literary corpora