The classic Masquerade pin
Masquerade has since been revised for second edition to end this pin combo.
This section is based on the strategy article originally written by Theory.
The key to the combo is that you trash down to a four-card deck of King's Court, King's Court, Goons, and Masquerade. Playing King's Court – King's Court – Goons reduces your opponent to 3 cards; now, playing a (Kinged) Masquerade forces him to pass you a card. But since you have no more cards in hand, you can’t pass him anything, but you can still trash the cards he gives you. Three times.
Essentially, what this combo does is trash three cards out of your opponent’s deck per turn, while starting him with a 0-card hand each turn. Played consistently, you can force your opponent into a 0-card hand every turn while you empty some non-terminal piles fors. Eventually, all the cards in their deck will be trashed.
There are several things that can substitute for Goons. Any discard-down-to-three attack will work, but Goons is the best because it allows you to score points without having to buy green victory cards. With Militia, for example, the worst case scenario is that you’ll be “resetting” the game, though of course you have a massive advantage since you have cards in your deck and your opponent doesn’t. Outpost is another way to get in enough plays of Masquerade to trash your opponent’s hand, and has the added benefit of being unblockable by reactions. The combo of Mountebank and Cutpurse can also work, since after a few King's Courted Mountebanks your opponent will start reliably drawing at least two Coppers in each hand.
Note that your deck doesn’t have to be just those four cards: cantrips (like Caravan, Laboratory or Pearl Diver) are very helpful in this setup because they allow you to have some KC targets for explosive draw, are cheap, and are good Masquerade fodder (rather than being forced to pass away a King's Court).
The combo, however, can be stopped cold in a couple of ways:
- Reactions will stop the discard attack. You still lose 3 cards per turn, but it’s nowhere as deadly. (Reactions will not stop the Outpost version of the pin)
- The combo does not work in multiplayer, unless your idea of victory is to destroy the person to your left and no one else.
- It is countered if your opponent can somehow hide his VPs on a Native Village mat or Island mat.
- Some Dark Ages cards with on-trash abilities can break the pin:
- The cards of the combo themselves are often a counter.
- King's Court enables crazy explosive megaturns: by the time your pin is set up, maybe he’s already used Combo: King's Court and Bridge to empty the Provinces, or maybe just used some source of +Buy to buy out all the Estates for a three-pile ending.
- Goons slows the pace of the game, taking you forever to get those King's Courts, and by the time you start getting it ready he might have already piled out and ended the game.
- Masquerade itself is a counter: while you are trashing down to a small deck of very valuable cards, you are very vulnerable to being forced to pass a valuable card to your opponent.
- Duration cards can help evade the pin: drawing only 5 cards from your Tactician is a bummer, but at least it gives you options, and +Buy to replenish some cards. And with King's Court, maybe starting with a 5-card hand is enough to draw your deck anyway.
- And even though your opponent has a 0-card hand every turn, it’s still possible for him to buy out the Curses, and that might end the game on piles.
Really, this combo highlights the power of King's Court more than anything else. Just like Combo: King's Court and Bridge, it’s a multiple-card combo that is devastating once pulled off.
 Other Pins
 Bureaucrat pin
Repeated plays of Bureaucrat can force an opponent to draw the same five victory cards every turn, and then put them back as you play 5 Bureaucrats.
Though discussed here and here, this pin is entirely impractical in a serious game. The Silver-gaining from Bureaucrat gets in the way of setting the pin up and maintaining it, and can prevent the pin from ever being set up. Tricks with Rabble or Minion can make the pin better, but at the cost of providing alternative strategies that are themselves better than this weak pin.
This pin was proposed on the forums by jomini.
The classic pin, described above, relies on playing dead Masquerades, ones played when you have no other cards in hand, discard, or on deck to pass; if you trash cards as you receive them you can then play additional dead Masquerades (i.e. using King's Court/Throne Room/Golem/Outpost). A new downside to these pins is the need to trash incoming cards; with Dark Ages a lot of cards can now break the pin when you pass them over.
Thinking about this and looking over Beggar’s strategy space, I started thinking if there was, perhaps an alternative pin that didn’t require the Masquerades to be played dead. My idea was simple – use Masquerade to pass my opponent a Copper, Cutpurse it out of his hand, pass another Copper, Cutpurse, etc. After 5 cycles of that, the opponent has no cards left and plays an empty hand. So say you play your deck (it’s an engine) and you come out with +13 actions and the following hand:
- 5 Masquerades, 5 Cutpurses, 2 Beggars.
Play the Beggars to gain 6 Coppers. Then play the following sequence 5 times: Masquerade (pass Copper) -> Cutpurse (opponent discards a Copper). This leaves you with your opponent’s hand to play (or trash). As long as your engine keeps hitting, you can keep giving your opponent unplayable Copper and stealing ever more of his deck. Worst case scenario is that you add one copper to your deck (you can’t keep any of your opponent’s cards and can’t trash the last copper gained from the beggars). Eventually, you will run out of copper, but by then your opponent has nothing but copper in their deck (usually), which you can just Cutpurse out.
The question then became - do you really need the Beggars? Sure they make it easier and cleaner, but, in theory, you could just use 5 buys and a strong, reliable engine to still draw everything and play the 5 Masquerades. Playing on Goko with strong boards for it (Masquerade, Throne Room, Nobles, Worker's Village, Quarry, Native Village, Courtyard), it took me around 15-18 turns to setup and was reasonably reliable with a Throne Room/Worker's Village/Nobles/Courtyard/Native Village engine. From there on out, it seemed like it would work most of the time with careful play. This suggests that the minimum needed to make this work is: a strong engine, lots of +actions, a source of copper (Beggars or +buys), Cutpurse, and Masquerade.
I’m not sure how this will play in real matchups and I don’t have time to try it myself heavily on Isotropic. So I’m posting this article in the hopes of getting feedback about viability and strategic implications.
Implications already known include:
- Moat and Lighthouse can completely hose the strategy. Without the Cutpurses hitting, you just get one card swap (often a C for a C). Horse Traders can make it weaker but not stop it.
- Duration cards can break the pin a bit. E.g. Tactician gives you a chance to muck up my deck. However, unlike the classic ultra-lean deck pin deck, I can still hand over a lot of cards from deck because I can either buy replacements or gain them back from your deck later so key Masquerade play won’t save you. Likewise, I can likely afford getting hit with Militia.
- Discard attacks, like Militia, make this far easier to pull off. Right now you need 10 cheapish cards and an engine strong enough to keep hitting them. With Militia (or any other discard attack) that number falls down to 7. Discard attacks also let the game last longer so you have more time to setup.
- Even if the pin misses for a turn, you really have to end the game quickly, because instead of burning VP cards, the victim is giving them away. Lead’s evaporate twice as quickly and as noted this is not an easy pin to disrupt.
- Haven, Scrying Pool, Scheme, Count, and any other engine reliability boosts are extremely useful for making the pin more reliable.
- Cards that let you mass cheap things easily are quite useful – Talisman, Quarry, Haggler, etc. can very quickly let you transition from a strong engine to the full pin in just a couple of turns.
- Secret chamber makes the pin more difficult and can require an additional 2 plays Masquerade (passing a Copper) to hit the pin.
 Possession + Forge pin
This pin was proposed on the forums by jonts26.
Masquerade? Discard attacks? Don't need them. What if I told you there exists a pin which requires you to increase your opponent's hand size? Crazy? Perhaps. True? Absolutely. Practical? Probably not.
The key cards are Possession, Forge, and Governor/Council Room. A King's Court won't hurt either. The pin works by a quirky little rule interaction involving Possession. A new 5 card hand is drawn during the clean-up phase. Cards trashed while possessed don't return until after your turn, AFTER you've drawn your 5 card hand. See it now? The idea is simple. Have your opponent draw his entire deck with Governor/Council room (that's where KC comes in handy). One of his cards has to be a Forge. Play possession. Forge away his entire deck. During his possessed clean up phase, he can only draw Forge. That's the only card in his deck. Only after clean-up is the rest of his deck returned to him. At best he can gain 2 Coppers.
This can also work with Count.
 Possession + Haunted Woods pin
Unlike the above pin, this does not require drawing your opponent's entire deck, and does not require your opponent having bought a certain card - you only need to make them draw 5 junk cards, then make them buy a card. Since you played a Haunted Woods during your turn, your opponent will be forced to top-deck their hand, and you'll make sure the 5 worthless cards go on top, so that when they finally get their own turn, the most they'll be able to do is buy a Copper. Just make sure you don't make them play their own copy of Haunted Woods, or they'll be able to draw 3 possibly useful cards.