|Type(s)||Action - Reaction|
Draw until you have 6 cards in hand.|
When you gain a card, you may reveal this from your hand, to either trash that card or put it onto your deck.
Watchtower is an Action–Reaction card from Prosperity. It is useful in certain engines and as a defense against many attacks—its Action effect defends against handsize attacks and its reaction against junking attacks. It reacts any time a card is gained, including when you gain one during your or another player's turn, allowing you to trash the card or put it on top of your deck. In some situations this will allow you to use the new card on your current turn (or at least the very next turn).
 Official FAQ
- When you play this, you draw cards one at a time until you have 6 cards in hand.
- If you have 6 or more cards in hand already, you don't draw any cards.
- When you gain a card, directly afterwards, you may reveal Watchtower from your hand, to either trash the gained card or put it on top of your deck (with Watchtower staying in your hand).
- You may reveal Watchtower whether you gained the card due to buying it, or gained it some other way, such as with Expand or Mountebank.
- You may reveal Watchtower each time you gain a card, and each gain is a separate decision; for example if another player plays Mountebank, you may reveal Watchtower to trash both the Copper and Curse, or just one, or trash one and put the other on your deck, and so on.
- Cards trashed with Watchtower were still gained; they were just immediately trashed afterwards.
- If a gained card is going somewhere other than to your discard pile, such as a card gained with Mine, you can still use Watchtower to trash it or put it on your deck.
 Other Rules clarifications
- Trashing a card with Watchtower does not prevent on-gain effects from happening.
- Watchtower's topdecking happens after the gain happens; the card still visits the discard pile, or whatever location it was gained to.
- Watchtower's topdecking has the same timing as on-gain effects, so for example you could choose to topdeck Death Cart before gaining the 2 Ruins.
 Strategy Article
Original article by theory
First, and most obviously, Watchtower is a devastating defense card against Curse-givers. Not only does it block the Curse from entering your deck, it actually trashes the Curse, meaning that an attack-heavy opponent will soon find himself running out of Curses to give. (Compare to Moat, which, against a Witch-heavy player, only delays the inevitable.) Although it provides no defense against “deck-inspection” attacks (e.g. Spy, Thief, Pirate Ship, Rabble), it does subtly defend against handsize-reduction attacks by allowing you to draw back up to 6.
Second, if you’re willing to hold onto Watchtower and not play it, it works as a mini-Royal Seal, minus the . There are some ridiculous ways to take advantage of this; most powerful is probably playing a Talisman, buying a Treasure Map, gaining another one, and putting them both on the deck! More commonly, you can buy something like Village/Smithy or Throne Room/[some other action] and ensure that you draw them together next turn. Even when you just have one buy, Watchtower can make sure you play important attack cards before your opponent gets a chance to.
Third, and this is a very specialized use, Watchtower greatly increases the power of Goons. Ordinarily, Goons-heavy players will avoid buying too many Coppers for VP tokens for fear of weighing down their deck. Watchtower solves this problem by trashing the Coppers as they come in, while still collecting the VP tokens.
Finally, Watchtower can form part of a good card-drawing engine. Although Library is superior (both because it draws more cards, and also because it can discard unwanted Actions), Watchtower is much cheaper and fulfills other roles as well. In addition, drawing a dead Watchtower (either because you have no Actions left, or because your hand size is very large already) is much less of a liability than a dead Library because of its other uses, as noted above. It is especially useful with Vault.
With the release of Dark Ages, Watchtower gained a new use - activating on-trash abilities : ▪ Ironworks a Fortress, and instantly trash it to put it in your hand ! ▪ Workshop a Feodum, and instantly trash it for three Silvers, which can go directly on top of your deck ! ▪ Upgrade a Fortress into a Cultist... and instantly trash the Cultist for +3 cards ! ▪ Use a spare Buy to buy a Curse, instantly trashing it to activate your Market Square ! ▪ Buy and trash a Squire, and gain a topdecked Familiar without even needing a Potion !
- Festival, Fishing Village, University, and other +Actions that do not draw cards
- Especially University, since the combo allows you to gain a Action, top-deck it, draw it, and immediately play it.
- Talisman, or other sources of multiple Buys
- Opponent's Curse-giving attacks (Witch, Mountebank, Torturer)
- Handsize-reducing attacks (Militia, Goons, Torturer, Ghost Ship)
- Cards with when-trashed abilities: Feodum, Market Square, Fortress, Rats (sort of), Cultist, Sir Vander, Squire.
- Cards that increase hand size (e.g., Laboratory/Alchemist, Caravan/Wharf, Tactician)
- Attacks that it does not defend against (Pirate Ship being the most important)
- Royal Seal, since the benefit becomes a bit redundant
- Library, since Watchtower is an inferior engine card
- Throne Room, King's Court, Royal Carriage, as the additional plays don't allow drawing of more cards
 Alternate versions
 In other languages
- Czech: Strážní věž
- Dutch: Uitkijktoren
- Finnish: Vartiotorni
- French: Mirador
- German: Wachturm
- HiG translation error : "When you gain or buy a card, ..."
- Italian: Torre di Guardia
- Japanese: 望楼 (pron. bōrō)
- Polish: Strażnica
- Russian: Сторожевая Башня (pron. storozhevaya bashnya)
- Spanish: Atalaya
 Secret History