(work in progress)
LET'S OVERHAUL THIS BITCH
This is Death Cart; look upon its works, ye Mighty, and despair. Death Cart provides the single largest +Coin benefit of any card, barring variable Coin producers like Vault and Secret Chamber. It is one of the new Looter cards from Dark Ages, and the only one that is not an Attack. It instead gives Ruins to the buyer, which, along with the choice to either trash it or another Action card when played, is meant to serve as a counterbalance to the ridiculous amount of Coin it produces.
What does it do? Death Cart, unlike many Dark Ages cards, is pretty straightforward. Trash Death Cart or another Action, +$5. Unlike trashers like Chapel, Count or Remake, the intent of Death Cart is not to clear your deck of junk - the intent of Death Cart is to produce money, with a little sacrifice required, in the vein of cards like Salvager. Sometimes the sacrifice is easy - when you have a Ruined Village in your hand with it. Sometimes the sacrifice is hard - when you have a Mountebank in your hand with it. Do you trash the Mountebank, or do you get your final use of Death Cart?
Now compare Death Cart to a similar card - Baron. Baron costs $4, gives a fairly ridiculous amount of Coin, and discards a specific card. This means it doesn't have to keep looking for fuel, like Death Cart does, and Baron can even generate its own fuel when running low. Add in a +Buy, and you start to wonder whether the extra +1 Coin is worth it. It is. It really, really is. To be fair, on a board with no cheap Actions and no Village, I would probably choose Baron over Death Cart, just because I would get more use out of him. But for Baron and Death Cart to appear in the same kingdom with such a setup is very rare, so the point is practically moot. For most boards, Death Cart will be superior, simply because that extra +$1 makes it that much easier to snag a Province.
But the fact that Death Cart trashes is important, so let's make another analogy - to Moneylender. Moneylender is a great opening card, as your deck starts off full of fuel for it - fuel which you're only too glad to get rid of. But whereas Moneylender starts off with 7 uses, Death Cart starts off with only 3, and 2 of those come at the cost of
adding junk to your deck. So Death Cart is not going to slim your deck down.
The Duchy rush gets a lot easier with Death Cart, as it does with Altar. A Death Cart in hand at least guarantees a Duchy, so if you're having trouble getting the extra coin in your hand to make it to Province, go for a three-pile of Duchies, Death Carts and Ruins, which will empty in just five Death Cart buys, barring usage of Trader.
When should I buy it? Death Cart can be a massive help on certain boards, but there are certain instances where Death Cart is a must buy. If your Death Cart is to last long at all, it needs Actions to trash. When is your deck going to be filled with Actions? In an engine. In order for an engine to work, it usually needs +Buy, and in a Death Cart engine, those +Buys can often be spent on cheap Actions - preferably non-terminals that won't hurt your deck. A standout example is Haven - it can either be fed to the Death Cart on a turn that will field $8, or save that Death Cart for next turn. Sifters like Cellar or Warehouse are less good for this, for, while they can get you to Actions to trash or can be trashed themselves, they decrease your handsize, thus decreasing your chance of making $8 this turn. But an engine is supposed to be drawing your entire deck anyway, and in that context, Death Cart can easily net you an extra Province or Duchy each turn. Alternative ways to acquire cheap Actions, outside of using +Buys, can be very helpful, such as with Ironworks. Gainers are especially nice because they can create Death Cart fodder for this turn, rather than next turn, as a +Buy would.
Also be aware that you should not go out of your way to find fodder for Death Cart. If you have more than $2 or $3 to spend with your final Buy, it should probably be spent on a Victory card, a Treasure, or an engine part, rather than on a cheap Action. It is usually better to just let Death Cart self-trash than to try to buy out the Pearl Divers. And in the end game, you may find yourself feeding more expensive Actions to Death Cart, simply because doing so is better for getting those Provinces. It may sometimes be better to feed a $5 Action to the Death Cart in the final turns so you can Scheme that Death Cart for next turn, rather than allowing it to self-trash. Other times, self-trashing is the correct move. It will depend heavily on how the Provinces are split at the moment, how many are left, and how close you are to a reshuffle.
Perhaps the single best combo with Death Cart is Rats. What does Death Cart want to eat? Useless Actions. What does Rats do? Fill your deck with useless Actions. I may not have made this clear enough in my Rats article, but Death Cart/Rats is a quite powerful combo. When these two are on the board, Rats should be your first $4 buy, and Death Cart should be your second. Give preference to trashing Rats over the Ruins, as the Ruins will be more useful to you than the Rats, and the Rats draw you a card when trashed, which is a nice little bonus. The Rats should also be given trash preference because if they aren't, they'll quickly overrun your deck. Ironworks can fill a similar role, in that it can produce lots of copies of itself, but the key differences here are that 1) There are only 10 Ironworks in the pile, and 2) Rats replaces cards, while Ironworks adds cards, so Death Cart will find Actions to eat a lot more often with a Rats deck.
The second best combo with Death Cart is Fortress. Fortress is infinite fuel for your Death Carts, and provides the +Actions necessary to guarantee Province buys. But beware - oftentimes such boards also have engines and other trashers to take advantage of Fortress - Salvaging a Fortress will net $1 less, but gives a very crucial +Buy that can pick up the winning Duchy. An engine strategy using other cards on the board can beat a non-engine Death Cart strategy, so if you need to spend a couple turns picking up engine parts to draw your Death Carts more often, do so.
Death Cart is also a great defense against Looters - not only does a Death Cart buy decrease the Ruins pile substantially in the first place, but a Death Cart can turn those nasty Ruinses into wonderful coins for buying Provinces.
Now, there are two meanings of "when" here - we've address the sense of "in which kingdoms," but not "on what turn." Opening Death Cart is usually not a good idea, unless you're using it to self-trash into a better card. You typically want to wait until you have at least the beginnings of an engine before adding Death Cart to the mix - that way, the Ruins will hurt less, and you'll be more likely to make that Death Cart hit fodder.
Should I ever buy Death Cart outside the context of an engine? Usually not. Death Cart/BM is not a good strategy. Adding Treasures to your deck decreases the chances of your Death Cart ever seeing those Ruins, or any other Actions for that matter, quickly turning Death Cart into either a one-shot or a useless card in your deck, along with two Ruins. Now, Death Cart can be used as a slingshot card, like Mining Village or Feast, to get you to the better cards in the kingdom, but unlike those other cards, it comes with junk, which, once your Death Cart is gone, you now have no way to get rid of.
How can I counter it? You might be tempted to buy out a pile of cheap Actions to deny the Death Cart player fuel, but even if you were successful at that, a self-trashing Death Cart will still be useful to them, and you’ll be stuck with cheap Actions and no real economy.
As for countering with Attacks: Looters are absolutely useless against a Death Cart deck, as all they're doing is giving the Death Cart a longer lifespan. Discard Attacks can help, but a hand of Death Cart, Gold, and a crappy action can still net a Province. Even without the Gold, the Death Cart can still pick up a Duchy. A lucky Saboteur could knock out a Death Cart, but unlike using Saboteur against Rebuild, there's too much other stuff for Saboteur to hit that the Death Cart player won't mind losing. The best Attacks to use against Death Cart are Cursers and Ambassador, as the deck-clogging will make it harder for them to get to their Death Carts, and harder for them to line up their Death Carts with suitable targets. Mountebank is the king here, as Curses and Coppers are equally useless to a Death Cart player, though extra Coppers could give a self-trashing Province buy. If you can make it work, Swindler is also a standout, as it can turn Ruins and Coppers into Curses, or Death Cart into a Potion. However, this does limit you to the luck of whatever happens to be on top of your opponent's deck. And a chain of Rabbles could leave your opponent with a hand full of Victory cards, leaving them nothing to feed to the Death Cart, and not enough funds to buy a Province.
Other combinations: Like with any trashing card, Market Square is very nice with Death Cart - it gives +Buy, gives you a Gold (which is nice if you have to trash an Action you didn't quite want to, besides making it that much easier to hit $8), and in a pinch can be fodder.
Band of Misfits is nice with Death Cart - if you don't feel like picking up Ruins, you can instead pick up a Band of Misfits and use it as a Death Cart when the hand to do so arises.
Works well with:
Rats
Fortress
Market Square
Band of Misfits
Haven
Engines
Action gainers
Counter with:
A solid engine
Cursers
Ambassador