A namburbi never argued that an omen was false. Mesopotamian divination read the world as a text the gods had written, and a diviner's job was to read a sign correctly, not to dispute that it existed. What a namburbi offered instead was a second stage of the same theology: the gods who sent a warning could also be petitioned to withdraw its consequence, provided the ritual specialist addressed them correctly.
A typical namburbi opened at dawn facing Shamash, the sun god who saw and judged everything, with offerings set out and an incantation naming the specific portent to be undone. The rite then physically enacted the release it asked for, most often by carrying a substitute object, sometimes a figurine, sometimes the material remains of the offending sign itself, out to open country or into flowing water, on the logic that evil disposed of outside the settled, ordered world could no longer act on someone inside it. Girra, the fire god, frequently featured alongside Shamash because burning, like flowing water, was one of the standard Mesopotamian methods for permanently destroying a ritual danger rather than merely displacing it. The ritual's wording often addressed the omen itself directly, commanding it to depart to the steppe or the river, treating the portent almost as an independent agent that had to be persuaded or compelled to leave rather than a passive fact to be merely canceled on paper.