If both draw decks are empty and no one has claimed victory, then you win if you have the most Patron prestige, and if tied, most florins.
You must buy and discard a comet to activate a victory condition. If a comet falls out of the market, then an opportunity to activate one is lost.
Holy Victory - You must have the most prestige in the supreme religion. The supreme religion has more bishops of one color in play than the other two colors combined, and it also has more knights, rooks, and pirates of that color in play than the others combined. Repressed tokens do not count.
Imperial Victory - You have at least 2 more kings (3 kings in a 2-player game) than the next highest player.
Globalization Victory - You have the most Discovery prestige and at least 2 more concessions than the next highest player.
Renaissance Victory - You have the most republics and at least 2 more Law prestige than the next highest player.