Domains: The measured dose, the assembly's vote, the curve of water.
Era of ascension: Great Expansion. Cohort: current. Elvanweir consolidated as the Eloweir refined two civic disciplines in the same generation — toxin-craft and assembly governance — and discovered, with some surprise, that they were the same discipline differently applied.
Worshipped by: The Eloweir, in the assembly-halls and in the apothecary-courts that adjoin them. The Eloweir maintain that the worship is civic, not popular; the patron is invoked through the institution rather than through individual prayer, and an Eloweir who keeps a personal shrine to him is considered to have misunderstood the religion. (The worships edge is authored downstream on the worshipper, not here.)
Poison and democracy, on the Eloweir account, are the same craft: the precise application of a controlled substance, where the substance is sometimes a tincture and sometimes a proposition. Too little, and nothing happens; too much, and the patient dies. The work in both cases is the dose. The assembly's vote is calibrated the same way an antitoxin is, by knowing precisely how much of the opposing element the body politic can absorb without seizing, and administering exactly that. The patron is the calibration.
He is not Gavelos. Gavelos is the patron of trade-sea, of safe passage between markets, the human Romance mariners' navigator. His domain is the sea as a road from one place to another. Elvanweir is the sea as a worked substance: water as the medium in which dosage occurs, the salt-curve of an Eloweir coastal canal where the tincture-springs are gathered. A Gavelos shipping captain who docks at an Eloweir port is honored as a guest. A Gavelos captain who tried to take a draft from a tincture-spring would be poisoned by mistake, not malice, because the captain would not know which spring on which day was tuned to which dose. The Eloweir would not blame the patron. They would blame the captain for failing to ask.
The cultural inflection is that the Eloweir assembly does not vote by simple count. The vote is weighted by office, by tenure, by the topic's calibrated importance, and by a margin the priesthood of Elvanweir adjusts annually. The margin is the dose. A measure that passes by exactly the calibrated margin is considered to have passed correctly; a measure that passes by a wider margin is examined for whether the assembly was over-applied. The priesthood does not overturn such measures, but it does record them, and the next year's calibration is adjusted to bring the assembly back toward the measured dose. To an outsider this looks like the priesthood holding veto power. To an Eloweir it looks like the priesthood doing its job, which is the dose.