De Vermiis Mysteriis

Current Holder: Georgiana Wentworth

Origin: Recovered during the London investigation (Chapter 1)

Physical Description

A Latin text in heavy quarto binding, the leather dark with age and stamped with faded geometric patterns that do not correspond to any standard bookbinding tradition. The pages are thick rag paper, browned at the edges, with woodcut illustrations of unsettling precision — anatomical diagrams that blend human and non-human structures, ritual configurations rendered in technical cross-section, and sigils that appear to shift slightly in peripheral vision. The text is dense, scholarly, and written with the clinical detachment of a man describing procedures he has personally performed.

Provenance

Attributed to Ludwig Prinn, written c. 1542 and first published (suppressed) in Cologne. This copy is a Latin edition, likely 17th century, recovered during the Chapter 1 London investigation. It was in the party’s possession by the time they reached Vienna and was among the items seized from their rooms at Palais Kinsky during the Polizeidirektion search (Session 4).

CoC 7e Tome Statistics

(Source: CoC 7e Keeper Rulebook, Mythos Tomes)

Campaign Relevance — The Counter-Ritual

The De Vermiis Mysteriis is the party’s only source for a potential counter to the Harmonic Engine. As established in the Session 11 assault planning scene:

• A partial counter-ritual exists in the text — a harmonic inversion that could theoretically disrupt the Engine’s resonance. Prinn describes it as a method for “unmaking that which has been bound by sustained tone,” originally intended for dismissing entities summoned through harmonic means.
• The counter-ritual requires three things: the fork, a specific sequence of strikes (described in the text as a “contrary pattern”), and physical proximity to the Engine.
• The cost is not specified. Prinn does not describe what happens to the person performing the inversion. The text says only that the binding must be “returned through the instrument that shaped it,” which implies the fork acts as both weapon and conduit.
• Georgiana’s connection: The counter-ritual is the inverse of what she did when she controlled the Wächter — pushing instead of pulling. The implications for her psychic bond with the Engine are unclear and frightening. Using the fork to disrupt the Engine may deepen the bond catastrophically, or it may sever it. The text offers no guidance.

Known Uses in Play

• Chapter 1: Recovered during the London investigation (exact scene unconfirmed).
• Session 4: Stolen from the party’s rooms at Palais Kinsky during the Polizeidirektion search.
• Session 10: Recovered from the Polizeidirektion using Metternich’s writ.
• Session 11 (planned): Available for Georgiana’s research during assault planning. Partial study yields the counter-ritual fragments.

Session 12 Update — Studied at Thaliastraße 12 (11 August 1814)

Adrien studied the De Vermiis Mysteriis during the forbidden texts study session at Thaliastraße 12 on 11 August.

Intelligence Revealed

• Counter-frequencies: The text describes tonal inversions that collapse harmonic fields. This is the specific technique Prinn calls “returning the binding through the instrument that shaped it.” The counter-ritual the party is planning for the assault is grounded in this passage.
• Operational detail: The strike sequences described are the “contrary pattern” required by the counter-ritual. Adrien now holds this knowledge, alongside Georgiana, who holds the fork.

Sanity Cost

Adrien suffered a severe mental break during the study. He fainted. When unconscious, traumatic memories from a Pyrenees abbey were projected visually onto the parlor window, visible to anyone present. The episode has implications for Adrien’s state going into the assault.

Known Uses in Play (Updated)

• Chapter 1: Recovered during the London investigation (exact scene unconfirmed).
• Session 4: Stolen from the party’s rooms at Palais Kinsky during the Polizeidirektion search.
• Session 10: Recovered from the Polizeidirektion using Metternich’s writ.
• Session 12: Studied by Adrien on 11 August. Revealed counter-frequencies and tonal inversions. Adrien suffered severe mental break: fainted, traumatic Pyrenees abbey memories projected visually onto the parlor window.