Like most other $2 Actions, Cellar is a versatile card. Early game, it cycles through your deck so you can quickly play your newly-bought cards. Mid-game, it fixes unlucky draws in order to set up your engine. Late-game, it helps you avoid your Victory cards to scrounge together enough money to end the game.
The efficacy of the card is directly tied to your hand size. Cellars are best with large handsizes; for instance, a Laboratory/Alchemist chain or a +Actions/+Cards engine. In games with smaller handsizes (e.g., Militia-/Goons-heavy games), Cellars are more of a liability than a benefit.
Note that you need not actually discard any cards to the Cellar; this can be useful to lower the price of the Peddler or to activate a Conspirator chain.
One of Cellar’s best features is its ability to control reshuffles. Suppose you draw a hand of 4 Victory cards and a Cellar, and you have no more cards left in your draw deck. Instead of Cellaring all 4 Victory cards, you can instead Cellar exactly 1 Victory Card, thus triggering the reshuffle, and then end your turn and discard your hand (which will hopefully still be junk). The quality of your draw deck is thus improved because you have kept a hand full of Victory cards out of the reshuffle.
Players that draw two or more Cellars in a single hand often face a decision of whether or not to Cellar the other Cellar. The answer depends on your deck composition and how many other cards you are Cellaring. Cellaring the other Cellar allows you an extra card in your hand, but saving the other Cellar allows you a second chance to draw. Generally speaking, if you are Cellaring more than two other cards, you should almost always save the other Cellar; if you are Cellaring only one other card, you should probably Cellar the other Cellar as well.
Cellars are also useful in crappy decks that have been Witched or Mountebanked. It’s completely worth giving up one slot in your hand in order to be able to cycle through your bad cards.
The biggest drawback to Cellar is that it’s been largely outclassed by Warehouse, whose ability to draw 3 cards and look at them before discarding means that Cellar is superior only if you’re discarding 5 or more cards at once.
- Cards that increase hand size: e.g., Laboratory/Alchemist, Caravan/Wharf, Tactician
- A 5/2 split, because it lets you cycle through your deck faster to play your $5 Action again
- Libraries, which weed out unwanted Actions but not unwanted Treasures or Victory cards. Cellars can alleviate the problem of a late-game Library drawing nothing but Victory cards.
- Curse-based attacks
- “Dense” decks, e.g., Market-based decks, where the lowered hand size hurts
- Opponents’ handsize-lowering attacks (Militia, Goons, Torturer, Minion, Ghost Ship)