The Boril’s Synodicon is a fragment of a manuscript, which originated from the literary circle around Euthymius, the last Bulgarian Patriarch before the fall of the Second Bulgarian Kingdom under the Ottomans. The document testify about the anti-Bogomil Synod, convened by King Boril in 1211 in Tarnovo (Bulgaria). Compiled on the occasion of the Council, revised at the reign of Ivan Assen II and complemented in the late fourteenth century at the time of Patriarch Euthymius, it is a testimony of the official attitude against the heresies in Medieval Europe and of the liturgical use of this specific political and religious instrument in the medieval Slavic societies, as it influenced the Serbian and Russian redactions of the Synodicon. Dated to the reign of Ivan Shishman (1371–1395), it contains polyhronia. The book also contains beadrolls of high historical value with the names of Bulgarian rulers and clerics. According to its liturgical purpose, the copy is supplied with the unique Coronation Rite of a Queen. In addition to its historical importance, the bilingual manuscript (Greek and Bulgarian) serve in witness of the cultural influence of Byzantium, especially by its unique notated texts, a testimony of the spreading of the Byzantine melismatic chant in the Balkans during the Middle Ages.