Gaven and his party could only hope that the rulers of Posku City would make such a foolish move.
If they ever took Posku, they wouldn't return it like they did with Efanso, but would instead occupy it directly and station troops there. After all, as a border city, it only needed to be defended on one side, unlike Efanso, which faced enemies from all directions.
Then they could secure their own retreat, and in case the battle in the Goblin Margins turned against them, they could fall back.