Buy phase synergy is ordinarily a product of three factors: +Buy, cost reduction (e.g., Quarry), and buy duplication (Talisman). Increasing a single factor provides negligible benefits; no matter how cheap Peddler is, if you have only one Buy, it might as well cost you all the money in your hand. Increasing multiple factors, on the other hand, leads to explosive results. (See, e.g., Quarry/Talisman).
The reason Goons is so powerful is because it adds a fourth factor: VP per buy. So on its own, Goons is a decent card, a combination of Militia and Monument. But with other Buy phase synergy factors, Goons becomes a devastatingly effective card for churning VP. When building a Goons deck, you don’t need to bother with Victory cards: you’re looking to make the game drag on as long as possible, because you’re spending each turn buying more Actions to boost your Goons engine. As your deck gets stronger and stronger, you will earn more and more VPs every turn. Because of this, you should try to avoid buying Coppers too early, because it needlessly gums up your deck (and you’ll probably earn more VP for it later). If the support cards are present, aim for a massive final turn where you buy out the piles while collecting a ton of VPs (50+) from Victory cards and Copper buys.
Goons decks depend heavily on +Actions, and ideally, +Cards as well. Without the ability to play multiple Goons per turn, you’ll usually only be able get multiple VP chips by buying Coppers. In addition, your Goons buys might end up actively hurting your deck unless you can find a way to play all the Actions you are buying. City works especially well for this: it provides you both with +Actions and has an excellent chance of leveling up and providing you the card draw you probably need to play all your Goons. In the alternative, if there just aren’t good non-terminals left for you to buy, trash-for-benefit cards like Salvager and Apprentice are a good way to clear out some of the junk you’ll find yourself buying.
Finally, Goons/Watchtower is a brutal combo if and only if the above conditions are met. Watchtower alone cannot turn Goons into a viable card, but it can turn Goons from a viable card into a devastating one.
- +Actions (especially Fishing Village and City)
- Other Buy phase synergies
- +Buy (especially City and Bridge)
- Cost reducers (e.g., Quarry, Bridge, and Peddler)
- Non-terminal Actions to soak up the +Buys
- Council Room
- Opponent’s Library
- Lack of +Actions, or terminal Actions in general
- Gardens and Duke/Duchy decks: not only is the attack nullified by their Victory cards, they’ll look to end the game on piles before your engine reaches top speed