If during your turn the total Succession Points from all of the cards in your Domain (including your Princess Card, Territory Cards, etc.) is 20 or more, you can declare a coronation ceremony.
If you have Farming Villages, Apprentice Maids, or other cards that subtract Succession Points in your Domain, they reduce your total by that amount. If, after you declare a coronation ceremony, all of the other players get to take their turns without being able to declare coronation ceremonies themselves, you win the game. If multiple players have declared a coronation ceremony, the game goes into sudden death overtime.
If, during the time when the other players are taking turns your Succession Point total goes below 20, your coronation ceremony is negated, and the game continues.
Example 1: You are backing First Princess Lulunasaika (6 Succession Points), and in your Domain you have 1 Farming Village (-2 Succession Points), 1 Duke (6 Succession Points), and 1 Senator (3 Succession Points). Your current total is 13 Succession Points. You need 7 more Succession Points to hold a coronation ceremony.
Example 2: There are three players, A, B, and C. Player A gets up to 24 Succession Points and declares a coronation ceremony. To his right is Player B, who has 20 points, and also declares a coronation ceremony. Player C has only 12 points, and cannot declare a coronation ceremony. In this case, when Player A takes his next turn, the game goes into overtime with only Players A and B.