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A Hecatombist is one of Tesh's most elite and highly-ranked thaumaturges, especially notable given the city-state privileges those with thaumaturgical talents. They have the knowledge and ability to summon Phasma Urbomachs - also known as Thysiacs, murderspirits, or massacre spirits, albeit at great cost to themselves and presumably culminating in their deaths. The only Hecatombist seen in the Bas Lag Cycle is Spiral Jacobs.


See also: Teshi thaumaturgy

Given the mysterious nature of Teshi thaumaturgy, it is not known whether Hecatombists are able to use their skills independent of the Hecatomb ritual. As the Teshi monk Qurabin describes the Hecatombist's arts as "the finishing of the law", it is possible that their abilities are a type of acausal boon granted by the Phasma Urbomach in return for its summoning; notably, Spiral Jacobs is only seen using his considerable talent once his ritual is already well underway, which include bending space to traverse the city and dodge attacks.


The ritual used by Hecatombists to summon Urbomachs takes months of preparation and exacts a heavy toll on the mind of the summoner. The ritual involves the drawing of complex spirals and branching whorls, a sort of Teshi-Thaumaturgical language, at key locations around the city to be destroyed.

As an acausal effect of the to-be-successful ritual, "haints", colorless manifestations of everyday objects, are sent backwards and forwards in time from the moment of the summoning. While the haints only manifest for seconds to minutes at a time, they can kill by draining the color and life of whatever they touch or nearly touch.


In Iron Council, the Urbomach's summoning begins to transform the entire city of New Crobuzon into a sort of city-predator. The summoning causes lamp posts to begin to seem like teeth, brick walls to take on the attributes of an animal's flanks, and the lights of buildings and factories to become like glints of light in the eyes of a predator.

Known hecatombists[]

  • Spiral Jacobs - The Teshi ambassador to New Crobuzon who has lived in the city as a vagrant for several decades.