Peruvian heavy metal band Hadez with track corresponding to murderous ritual, court of Catherine de Medici.

Blavatsky writes of event thus, ISIS Unveiled, vol II:

Catherine, the pious Christian–who has so well deserved in the eyes of the Church of Christ for the atrocious and never-to-be-forgotten massacre of St. Bartholomew–the Queen Catherine, kept in her service an apostate Jacobin priest. Well versed in the black art, so fully patronized by the Medici family, he had won the gratitude and protection of his pious mistress, by his unparalleled skill in killing people at a distance, by torturing with various incantation their wax simulacra.

[King] Charles was lying sick of an incurable disease. The queen mother who had everything to lose in the case of his death, resorted to necromancy and consulted the Oracle of the Bleeding Head. This internal operation required the decapitation of a child who must be possessed of great beauty and purity. He had been prepared in secret for his first communion, by the chaplain of the palace, who was apprised of the plot, and at midnight of the appointed day, in the chamber of the sick man, and in the presence only of Catherine and a few of her confederates, the Devil's Mass was celebrated. Let us give the rest of the story as we find it in one Levi's (Elias Levi) work: "At this mass, celebrated before the image of a demon, having under his feet a reversed cross, the sorcerer consecrated two wafers, one black and one white. The white was given to the child, whom they brought clothed as for baptism, and who was murdered upon the very steps of the alter, immediately after his communion. His head, separated from the trunk by a single blow, was place, all palpitating, upon the great black wafer which covered the bottom of the paten, then placed upon a table where some mysterious lamps were burning. The exorcism then began, and the demon was charged to pronounce an oracle, and reply by the mouth of this head to a secret question that the king dared not speak aloud, and that had been confided to no one. Then a feeble voice, a strange voice, which had nothing of human character about it, made itself audible in this poor martyr's head." The sorcery availed nothing; the king died, and Catherine remained the faithful daughter of Rome.

Le Demonomanio, ou traite des Sorciers - Bondin