A mid-reign (also a mid reign or midreign) is an event held halfway through a reign. It's traditionally celebrated with a feast and court. In larger groups and at the Kingdom level, it usually means a weekend-long camping event. Midreigns are held every 6 months. Prime Minsters usually being their term of office at the Midreign, thereby overlapping the term of the monarch, regent, and champion.
The events of a mid-reign are rather universal among different chapters, though local traditions are common. At many mid-reigns, there is a battlegame tied to the events of the current monarchical reign. There is also commonly a tourney of sorts, whether it be a competition of A&S or Warskills. There is usually a meal in the form of a feast, that can be served before, during, or after court.
Court during a mid-reign begins with the Monarch giving out the major awards for their reign; especially masterhoods, titles, and knighthoods, if the monarch is of kingdom-level. Monarchs will then dismiss the sitting Prime Minister, thanking them for their service. Then the monarch calls forth the incoming Prime Minister, and officially anoints them into their office.
Following court, there is often an after party, where people hang out and relax after the day's events.