This article is about the hidden costs of cheap cards that are often bought since they appear to be 'better than nothing'. This would typically be a 2 cost card that seems harmless but contributes little to the overall design of the deck. Cards that fit into this category could be pawn, pearl diver, haven, hamlet, and vagrant, but the principles could also apply to cellar, crossroads, apothecary, spy, wishing well, great hall, sage, scheme, oasis, or all villages. These cards look harmless enough since you can seemingly always play them to get a replacement card and action. Whatever benefit the card gives it seems better than nothing. Let's look at some situations where you need to think twice.
Terminal Draw
This is the simplest case that people can recognize. Action cards have no value at all when drawn into hand with no actions left to play them.
Top of Deck Attacks
Attacks by a sea hag, fortune teller, or rabble do more damage when an opponent draws the bad card into hand on the following turn. There is a line thought that if the bad card is unavoidable it might as well come now rather than later but generally this reasoning is false. In Dominion you want to play your good cards as soon as you can for incremental benefit.
Some cards naturally defend against top of deck attacks, such as golem, scavenger, chancellor, venture, and adventurer. Drawing from the top of the deck before playing those cards will forfeit that defense.
Reactions
Whilst you may be able to play your cheap action for +1 card during your turn, during any opponent's turn it occupies space in your hand and deck. This means that your reaction cards are slightly less likely to be in hand and revealed. This not only applies to your moats, fool's gold and tunnels but also provinces (vs tournaments), young witch banes, and curses (vs mountebanks).
Discards
Whenever have to choose cards to discard from a hand including your cheap card, this decision comes before you can play it for +1 card. It is again occupying space in your deck. You must often choose between discarding a card you know or the cheap card that will draw an unknown from the top of the deck. The loss of information leads to poor decisions. This becomes worse when the decisions become more pivotal such as a militia attack on a hand of {trading post, pearl diver, curse, silver, silver}: Keep the bad cards for trashing or keep the treasures for spending? The lack of information can also leave you gambling on card combinations such as baron with estate.
Discards can often be forced by your opponent with militia type attacks but it can also come from your own cards such as warehouse, storeroom, and embassy. When a navigator or cartographer reveals a cheap card from the top of your deck, a later card in the deck has been obscured. The same is true with apothecary and scout however the cheap card may also have prevented you drawing a later card into hand. (On the other hand, small drawing cards can provide great benefit when played after a cartographer, apothecary, or scout).
Unique card effects
2 cost cards are vulnerable to being swindled into estates and that might be a consideration. Golems and hunting parties will find your cheap action cards, for good or bad. Adding extra action cards to your deck is likely to change the results from tributes and ironmongers.
How much does all this matter?
These subtleties can often be ignored whenever you are buying a card for a good purpose. Cheap cards can often provide great value. Even minor value can outweigh some of marginal risks discussed here. Thinking through some of these concepts can often also highlight benefits instead of risks. However it is possible for weaknesses in your deck to be exposed turn after turn and that's when you need to be aware of the risks. Then you need the foresight to buy nothing instead of a card that you don't really need.
