We previously posted an article on Rebuild, but this is a more advanced treatment on how specifically to deal with a two-player “Rebuild mirror match” where both sides contest this extremely powerful card.  This article is written by ragingduckd and SheCantSayNo, originally posted on the forum.

Rebuild Mirror Matches

When Rebuild is on the board, you usually just have to buy it. Other engines have a reasonable shot in games with Colonies or Shelters, but Rebuild is always a force to be reckoned with. When Rebuild has the home-court advantage of a Province game with Estates, there are very few decks that can outrun it.

This means that many of your Rebuild games — particularly your Province/Estates games — will be mirrors matches. Most of those Rebuild mirrors will follow a fairly consistent script. Playing them well requires first understanding that script and then deciding how and to what extent any particular kingdom demands that you deviate from it.

We assume that you’re playing against one opponent, with no Shelters, no Colonies, and no game-breaking combos, and that you and your opponent are both going for Rebuild. I briefly discuss some the major deviations from this setup at the end.

Act I: The Duchy Race

Your main goal in the early game is to win the Duchy split. An empty Duchy pile is a Rebuild roadblock for your Estates, so the Duchies you buy during this phase are the only cards you can productively Rebuild for the rest of the game. Getting more than your share of those Duchies is a huge win.

Your other early-game goal is to clear out those pesky starting Estates. If you manage to win the Duchy split 5-3 while emptying your deck of Estates, you’re in an absolutely dominating position. Every Rebuild you play will turn a Duchy into a Province, so playing Rebuild five times gets you five Provinces and a virtual lock.

Buying a Rebuild with your first $5 hand is a good start on both goals. With your subsequent $5 hands, keep buying either Rebuilds or Duchies. With each $5 hand, ask “if I buy another Rebuild, will I get to use it on an Estate before the Duchies run out?” When the answer is no, it’s time to start buying Duchies instead.

Edit: SCSN has done a wide range of simulations that suggest a simpler approach: buy 2 Rebuilds and then all Duchies.  Situations where anything else is better appear to be extremely rare.

Common mistakes to avoid:

• Rebuilding Duchies into Provinces — Deliberately rebuilding a Duchy instead of an Estate is the biggest early-game mistake you can make. Your opponent will snap up five or six Duchies, leaving you with deck full of small treasures, VP cards, and nearly-useless Rebuilds, and then rebuild his Duchies into Provinces while you scramble to find an $8 hand.
• Buying Gold or any $5 action besides Rebuild — Unless you plan to skip Rebuild entirely, your early-game focus should be on Duchies (and Rebuilds that can gain Duchies). Even the game-breaking $5 terminals (see Combos below) should only be purchased after the Duchies are gone.
• Buying surplus Estates — If your opponent is also rushing Duchies, you probably won’t have time to rebuild four Estates. A fourth Estate can be valuable if in you’re well ahead or in danger of running out of Rebuild targets, but it should be approached with caution. If that extra Estate wins the Duchy split, it’s a hero; if it’s the one Estate you get stuck with in a 4-4 split, it’s a goat. A fifth or sixth Estate is wildly overoptimistic and almost always a mistake at this point.

Act II: Post-Duchy Strategies

With the Duchy pile empty, the remaining sources of VP are limited. Unless there are alt-VP cards or VP tokens, it’s down to the Provinces and the Estates. Each player wants to Rebuild his Duchies, but he also has extra production to use along the way. He can use that production for of any of of three major post-Duchy strategies:

1. Turbo Rebuild: Add Rebuilds and sifters to rebuild your Duchies quickly

There are 8 Duchies in play and 8 Provinces to be gained. Every time a Province gets bought or trashed by Rebuild, another Duchy’s dreams die. With Turbo Rebuild, your goal is to make it the other guy’s Duchies that don’t get turned into Provinces.

2. Rebuild-BM: Add treasures and productive actions to buy Provinces

It’s not easy to start buying Provinces when you have a deck full of Duchies and Rebuilds, but it pays off big. Rebuilding a Duchy into a Province is only +3 VP, but buying one is +6 VP. Buying one Province can be enough for the win after a 4-4 split, and buying two will more than make up for losing the split 3-5.

3. The Estate Blitz: Buy estates and end the game early by rebuilding your Provinces into other Provinces

With Duchies gone and rebuilt Provinces worth only +3, Estates constitute a respectable form of VP. In a Blitz, you piledrive Estates and play Rebuild naming Estate to run out the Province pile. If all goes well, your opponent won’t have time to buy or rebuild into those last couple Provinces, and your pile of Estates will carry the game.

Some general considerations that should inform your decision:

• The Duchy split — When you’ve won the split, Turbo Rebuild is usually the best continuation (assuming you don’t also have 2 or 3 surplus Estates for you Rebuilds to trip over). Five Provinces is a near-lock, if you can get there. If you can’t, then your Rebuilds will at least be productive right up to the end of the game. If you’ve lost the split, Turbo Rebuild isn’t going to close the VP gap, so go Rebuild-BM or Estate Blitz instead.
• The kingdom — Cantrip sifters accelerate your rebuilding, which strengthens Turbo Rebuild and the Estate Blitz. Strong drawing cards strengthen Rebuild BM. Baron allows for a hybrid Estate-BM strategy. A complete list of combos would be difficult to write and painful to read, but you can usually just look at a kingdom and figure out which strategies have good support.
• Your deck — If you have some extra Silver because you didn’t get to $5 on T3 or T4, you’re probably in a reasonable position to go Rebuild BM. If you managed to clear out all of your Estates, then Turbo is very attractive.  If you got caught with 2 or more Estates, they’re going to seriously get in the way of your Rebuilding, so you might avoid Turbo even if you won the Duchy split. On the other hand, you probably have a VP lead already and the opportunity cost of an Estate Blitz is relatively low.
• Your opponent’s strategy — If the first thing your opponent does after Duchies run out is spend $6 on a Rebuild, he’s telling you that he’s going either Turbo Rebuild or Estate Blitz. Your time is limited, so responding with Rebuild BM is questionable unless you already have a good start. If he buys a Gold or an Estate instead, that reveals his intentions too. It’s hard to give concrete rules here, but try to anticipate how your strategies will interact and choose accordingly. If you respond to Turbo with Turbo, for example, the game will be high-variance and lightning fast.

You only get a few turns to choose your post-Duchy strategy once and for all. Once you start filling up on extra Rebuilds and Warehouses, you’ll have a miserable time changing gears to buy Provinces. Similarly, once you start adding Estates, it’s awfully hard to use your Rebuilds productively. This why Estates should be approached with caution during the Duchies race — a deck that gets caught with 2 or more Estates is essentially pre-committed to a Blitz.

Act III: End-Game Tactics

Once the players have committed to their post-Duchy strategies, the game is mostly tactical. But these aren’t the usual “do I buy a Duchy or a Gold?” end-game tactics, and they require skills that don’t normally get a lot of practice.

Tracking your VP cards throughout your shuffle is key. Rebuilding a Duchy is always best, and it’s often possible to engineer that. It’s also rather embarrassing to name the wrong card and have Rebuild skip your whole deck. If this happens to you, check the log to see exactly what was in the deck that you just discarded; this will get you back on track. The VP counter won’t do your job for you, but the counter plus the trash will often let you catch up if you’ve gotten just a little lost.

Resist the temptation to purchase haphazardly. If you’re running an Estate Blitz and some freak shuffle gives you a $7 hand, buy another Rebuild or Estate anyway. Despite this aberrant hand, you’re in no position to buy Provinces and adding a Gold isn’t going to change that. Stick to the cards that are compatible with your strategy, even if you have to grossly overpay.

Assess your long-term prospects and Rebuild accordingly. Often you have to risk either hitting an Estate or a Province. Hitting an Estate is pretty much a wash, but hitting a Province brings the game closer to its end. Before you play your Rebuild, consider whether shortening the game is good or bad for you.

As a general rule, the player with the better deck wants a longer game. If you have extra Duchies or loads of treasure, you want time to turn that advantage into Provinces. If your deck is full of Estates or you’ve already rebuilt all your Duchies, you probably want to end the game ASAP. An ordinary end-game is usually a race to gain Provinces (or sometimes to 3-pile), but a Rebuild end-game is often a race between a player who wants to gain Provinces and an opponent who wants to destroy them.

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Game-Breaking Combos

Most Rebuild combos simply strengthen or weaken the various post-Duchy strategies, but there are a few that are simply so powerful that you have to scrap most of the script.

Rogue and Graverobber can regain your trashed Duchies. Turbo Rebuild is the only serious strategy on such a board, since you’ll have a continuous flow of Duchies to rebuild. For the same reason, Estates become a huge liability.  These guys are mid-to-late game buys, but with Duchies going to the trash constantly and with little else to do with your $5 hands, you’ll want to acquire two or more.

Duke is the only $5 VP in the game besides Duchy, so it provides Rebuild with the only alternate road from Estate to Province. With Duke on the board, you can flood your deck with Estates and your Rebuilds and they’ll continue being productive right up to the end. You’ll have some Dukes in your deck at the end of the game, so name Duchy when you play Rebuild and let your Provinces fend for themselves.

Tunnel, as werothegreat has already noted, turns Rebuild into a Gold machine. In a Rebuild game with Tunnel, there’s no actual rebuilding into Provinces. Just name Tunnel every time and flood your deck with Gold.

Feodum isn’t game-breaking per se, but deserves a mention here, as it’s rather strong and it doesn’t play like a normal Rebuild mirror. Edit: Rebuilding Feoda into more Feoda and then buying Provinces with the Silver seems to work rather well and usually beats a Duchy-oriented Rebuild strategy.  Ignore Duchies until late in the game and be more inclined to buy Gold, draw, and other actions that help you get to $8.

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Other Notable Situations

Colonies weaken Rebuild. It takes several extra turns to go from 4-5 Provinces to 4-5 Colonies, and it’s a whole lot easier for an engine to grab 4 Colonies in 19 turns than 4 Provinces in 14 turns. With 4 VP cards instead of 3, you also have a lot less control over what your Rebuilds hit.

Shelters weaken Rebuild because you no longer get a free Duchy with every early-game Rebuild you play. I’d estimate that Rebuild with Shelters is effectively 2-3 turns behind Rebuild with Estates. In the mirror, you should buy fewer early-game Rebuilds and buy more of your Duchies directly.  Edit: SCSN’s simulations suggest that Shelters don’t particularly hurt Rebuild.  When Rebuild is matched against non-Rebuild strategies, its win rate with Estates is almost exactly the same as with Shelters.

Nobles, Harem, and Farmland can all be rebuilt into Provinces. Buying these is usually at least as good as buying Duchies, so the Duchy race becomes less important and finding $6 to buy these with becomes more important.

Smaller Alt-VP cards should be added with caution. They can play the same role as Estates in a Blitz, but you can’t name both Estate and Great Hall. Every time your Rebuild trips over a Great Hall, your opponent gains time to grab the Province you otherwise would have trashed. Still, Rebuild games are usually close, so all three strategies are happy to grab some extra VP as the game draws to a close.