Attack is a card type. An Attack is a card intended to hinder the player's opponent(s), either by making their next turn worse in some way, or otherwise weakening their deck. However, not all Attacks are equal, and while some can be quite devastating, others can range from mildly annoying to borderline beneficial to other players, depending on the circumstances. Most Attack cards are Action cards. There are no special rules relating to Attack cards; they are simply a useful label to have so that other cards (mostly Reactions) can refer to them.
 List of Attack cards sorted by expansion
- Dominion: Bureaucrat, Militia, Spy, Thief, Witch
- Intrigue: Swindler, Minion, Saboteur, Torturer
- Seaside: Ambassador, Cutpurse, Pirate Ship, Sea Hag, Ghost Ship
- Alchemy: Scrying Pool, Familiar
- Prosperity: Mountebank, Rabble, Goons
- Cornucopia: Fortune Teller, Young Witch, Jester, Followers
- Hinterlands: Oracle, Noble Brigand, Margrave
- Dark Ages: Urchin, Mercenary, Marauder, Cultist, Knights, Pillage, Rogue
- Guilds: Taxman, Soothsayer
- Adventures: Warrior, Soldier, Bridge Troll, Giant, Haunted Woods, Swamp Hag, Relic
Attacks are often a crucial component of an engine strategy: an engine deck can take longer to build than an unimpeded Big Money deck; but an engine that frequently plays Attack cards can slow down an opponent's deck-building enough to make engine construction competitive. However, since they attack the opponent, strong Attack cards often have relatively weak (or even no) direct benefits to their owner's deck, slowing down deck-building from that direction as well.
Not every play of every Attack card will adversely affect (or even affect at all) an opponent, and some cards which can be used to hurt an opponent, such as Masquerade and Ill-Gotten Gains, are not Attacks. The fact that "Attack" is a card type becomes relevant in that certain cards have specified interactions with Attacks. Most of these are Reaction cards that can be revealed when an opponent plays an Attack to have some effect that usually mitigates or counters the adverse effect of the Attack; the main exception is Squire, which has an on-trash ability to gain an Attack.
All Dominion expansions have at least two Attack cards. The greatest density of Attack cards is found in Cornucopia, which contains three Attack cards out of 13 Kingdom cards plus Followers, an Attack–Prize. The lowest density of Attack cards is in Prosperity and Hinterlands, which have only three Attacks out of 25 and 26 Kingdom cards respectively. In Hinterlands, the non-Attack curser Ill-Gotten Gains takes the place of an Attack card; in Prosperity, Donald X. Vaccarino deliberately kept the number of Attacks low in order to make it easier to construct decks that can buy Colony, and to compensate, Prosperity has a large number of non-Attack interactive cards.
 Kinds of Attacks
There are 6 basic kinds of Attacks; some Attack cards belong to two of these categories. Donald X. Vaccarino explained 4 of them here in depth, including how to defend against them; the other two were speculated on here.
 Handsize attacks
Handsize attacks reduce the number of cards you have in hand on your next turn, thus reducing the range of options available to you on that turn. The majority of these make you discard down to 3 cards, and the victim chooses which cards to discard; thus multiple plays of such handsize attacks don't hurt the victim more than the first one. These include Militia, Ghost Ship, Goons, Margrave, Mercenary, Followers, and Sir Michael. Urchin makes you discard down to 4 cards. Minion is a variation that makes you discard down to 4 cards, but you can't choose which card to discard, because you discard your whole hand and draw 4 new ones. Pillage is a one-shot where the attacker chooses the card to discard; and Taxman forces everyone to discard a particular Treasure. Some handsize attacks can make victims continue discarding cards on multiple plays: Torturer stacks if the victim does not wish to gain a Curse; Cutpurse and Bureaucrat target Coppers and Victory cards respectively and on repeated plays can continue reducing your handsize as long as you have the targeted cards in your hand; Soldier is stackable, but only until your opponent is down to 3 cards in hand.
The strongest counters to most handsize attacks include Menagerie, which is more likely to grant +3 cards in smaller hands, and Horse Traders, which increases your handsize again once your next turn starts.
 Attacks that trash your cards
Trashing attacks usually trash one of the top two cards of the opponents' decks, directly combating their deck-building efforts. Donald X. Vaccarino has described it as challenging to create trashing attacks that aren't too random in their degree of effectiveness and don't totally ruin players' enjoyment of the game. This is accomplished in various ways: trashing can be restricted to Treasure cards (as in Thief, Noble Brigand, Pirate Ship) or to a certain price range (Knights, Rogue, Warrior, and Giant), or the Attack can offer the victim a replacement for the trashed card (Saboteur and Swindler).
 Attacks that give you junk
Attacks that add undesirable cards to opponents' decks hurt an opponent by weakening the turns on which they draw those "junk" cards, and by slowing their deck cycling. The majority of these distribute Curse cards and therefore are referred to as cursers; these include Witch, Torturer, Sea Hag, Familiar, Mountebank, Young Witch, Followers, Soothsayer, Swamp Hag, and Giant; the on-gain effect of Ill-Gotten Gains has the same function as these Attacks, though it is not itself an Attack card. Dark Ages does not contain cursers; instead, its junking attacks are Looters which distribute Ruins: Marauder and Cultist. Noble Brigand sometimes distributes Copper. A few junking attacks can distribute a variety of junk cards, including Curses under some circumstances: Ambassador, Swindler and Jester.
 Attacks that muck with your deck order
Deck order attacks attempt to ensure that weak cards are left on top of an opponent's deck, or strong cards are discarded, weakening their upcoming hands and denying them opportunities to play their best cards. Bureaucrat, Sea Hag, Fortune Teller, and Haunted Woods specifically try to put bad cards on the opponent's deck; Spy, Scrying Pool, Rabble, Oracle can make them discard whatever good cards are there while leaving bad cards behind.
 Attacks that make other players' turns worse
Turn-worsening attacks, though not addressed in his Guide to Beating Attacks, were mentioned by Donald X. in his Seaside preview. Until Adventures, there weren't really any Attacks that fit this category and not any others (obviously, a handsize Attack usually makes a player's turn worse). Attack-Durations and tokens make this category possible.
The main example here is Bridge Troll; it doesn't make players discard, it doesn't trash their cards or give them junk, and does nothing to their deck, but it certainly makes their turns worse. Swamp Hag also fits in this category; though it can often simply have the same effect as a Witch, there's a psychological component to essentially Cursing yourself, and the Attack gets stronger the more cards the player buys. The threat of a Curse can even make a player choose not to buy anything. Relic also fits here (as well as Raid, though it is not an Attack); rather than making a player discard directly, it prevents players from drawing in the first place. This can either make their current turn worse if they have draw cards, or their next turn if they do not.
 Attacks that lower other players' score
The only Attacks that lower opponents' scores in Dominion are cursers, though their effect as junking attacks is usually more important than the fact that Curses are worth negative victory points. Donald X. has said he's tried cards that lower scores directly, e.g. like a reverse Monument, but they "fluctuated between being too weak, too strong, and too much work to deal with."
 Defending against Attacks
The most direct way to defend against an Attack is with a card that lets you ignore its effects: Moat, Lighthouse, or Champion. However, these cards are not always in the kingdom, and Moat is usually considered rather weak, while Champion is rather tricky to acquire. As such, countering Attacks usually requires more nuance. Handsize attacks can be handily combated by Menagerie or a draw-to-X card, junkers can be thwarted by a heavy-duty trasher or a protective Watchtower, trashing Attacks can be countered with gainers, and deck-order attacks can be mitigated by sifters. All of these are embodied in Jack of all Trades, which Donald X. has revealed he designed as an "after-the-fact Moat." A number of different counters to specific Attacks have also been found.