Stoneward Post is a military outpost and prison in Vale Sangora — a held point of Brencis’s war where the story and the two forms of your day both come into play.
Why it matters
The post is the location of the Save Mert the Miller quest: Mert the Miller is a rebel contact held there, and freeing him matters to the rebellion side of the conflict.
The defining feature of the location is that both a daytime and a nighttime infiltration route target the tower — the same objective, reachable under the human and the vampire form. That makes it a good early read on how the day/night split shapes open-world objectives, and it fits the 30-day timer because the approach you pick can be matched to what you are doing the rest of that day.
The full quest details live in the first-act walkthrough.