Dominion ends when three stacks are empty or the last Province is bought. Whoever has the most victory points when that happens wins.
At some point, you are suddenly in the late game. In my Dominion games, the first purchase of a Province is often heralded with a cry of “first blood!” Throughout the game, victory point cards are worthless clutter in your deck, making your average hand worse. When the game ends, victory points are all that matters. All at once, it does not matter how many Gold you have, how awesome your combo is, or how you were going to buy four Provinces next turn. There is not a next turn anymore. Add up your victory points and see who won.
You can see the endgame coming, but it still catches some people by surprise, usually because they think they had one more turn. Two or three turns earlier, they needed to switch over to and endgame mentality, focusing on victory points, but they were still building combos and buying Gold. This is exactly where you want your opponents to be when you strike and exactly where you do not want to be.
Part of the value of Big Money is that you are always working towards the endgame. Your first question every turn is whether you can buy a Province. That is a winning mindset. That is one of the recurring themes of The Book of Five Rings: whatever you are doing must be working towards victory. Thinking about how to build your combo or how to get more money is only helpful if combos and money are going to make you win. If the game changes so that more money or a bigger combo will not help you win, you need to stop working on that combo or money immediately, or else your strategy is moving you further from victory.
The more players you have in the game, the more likely you are to reach the endgame condition of emptying three stacks, especially if you have good, inexpensive actions. In my experience, two-player games almost always end with the sale of the last Province. Once you are six to ten turns in, you need to start watching for either of those conditions and plan on being the one who triggers the end of the game.
You also need to be aware of what the current score is. If someone has more victory points than you do, do not end the game. If you do, you lose. Do not move the game to where they can end the game. Instead, you need to start the desperate measure of acquiring victory points in less efficient methods like buying Duchies or doling out lots of Curses. If you are in this situation, you have probably already lost, so start thinking about winning early.
Unless everyone is playing a strict Big Money, in which case you are probably going to win anyway, they have long term plans that they are putting together. They are buying cards with an expectation that there are enough turns left in the game to make them worthwhile. If you can be the one to define the timing of the endgame, you can spoil those plans. They just spent two turns building up while you spent those turns ending the game.
There is no Dominion equivalent of the zerg rush, but there is certainly the equivalent of building for a late game that never comes. If the enemy marches thirty marines into your base while you are building your fourth undefended spaceport, you deserve to lose. If you are still building your combo while your opponent buys his fourth Province, you deserve to lose.
In most games, you will win more often if you are looking more moves ahead. Dominion is one of those games.
Next week, we take a break from these strategic thoughts to discuss the mechanics of attacks and reactions.