The oracle resets at the same time each day, regardless of when you actually visit. This happens if you try to make an arena deck after the oracle resets but before you visit for that day. If you are playing while the oracle resets, the oracle will not show as visitable until you refresh the page. (The oracle reset about an hour ago, so if you spun your quantum pillar just before then, it is your oracle card for yesterday, and you will have a new one for today.)
