Domains: Threshold, doorway, the act of crossing.
Era of ascension: Golden Age of Man (~155,000 years ago). Cohort: dead. Died: God War & Long Winter (~75,000 years ago), when the polities ended, the doors that mattered closed, and the gestures that had constituted his worship had nowhere to land.
Worshipped by: The household traditions of the Golden Age across every culture that built doors — and the institutional gatekeepers: the city-wall warders, the embassy protocol-keepers, the border-crossing officials of polities that maintained formal borders at all. No living culture maintains his worship. (The worships edge is authored downstream on the worshipper, not here.)
Otho's iconography was the doubled lintel-mark: one stroke painted on the inside of a threshold, one on the outside, so that the god could read the crossing in both directions and know who was leaving as well as who was arriving. The rite was the brief touch-of-fingers to the lintel at every passage — performed thousands of times a day across the Golden-Age polities, never as a major ceremony, never recorded individually, and almost never mentioned in texts because everybody did it. The whole of his cult was distributed in this way. He was the only Golden-Age daemon whose entire faith-base was gesture-frequency rather than congregation-size.
The doctrine held that frequency itself was the worship — the god lived on the cumulative volume of small attentions, the way a flame lives on continuous small offerings of air. A neglected threshold was therefore a deconsecration, not a sin; the god simply withdrew his presence by degrees as the gestures fell off. His priesthoods were tiny because there was almost nothing to administer: an annual repainting of the lintel-marks on public buildings, the formal blessing of new doors, the rare formal complaint when a polity stopped maintaining its border-crossing protocols.
The Winter killed him on the day the doors stopped mattering. As the polities collapsed and the people emptied into refugee bands, there were no longer doors to touch — no lintels, no thresholds, no borders being crossed in any sense the rite recognized. The gestures stopped not because anyone refused them but because there was nothing to gesture at. The cumulative frequency that had been his god-body fell to zero inside a generation. Veldrath (later, in another cohort) is protection-as-shield; Otho was protection-as-correctly-crossing, and what he protected against was the wrong crossing rather than the wrong arrival. The cold made every crossing wrong by erasing the distinctions his rite had marked.