Upgrade is a higher skill card than it might initially seem. What it does is pretty basic: replace a card with a more expensive one, or trash it entirely if no card exists that costs $1 more (in particular $0 cards like Copper, Curse, Ruins). However, doing this effectively can be quite challenging, and many good players will look like they’re performing some kind of wizard voodoo with Upgrade. Don’t get scared. The thing to remember is that Upgrade is not a simple trasher like Chapel or Steward. Trashing $0 cards is icing on the cake, but not the moist, wonderful center. In its best form, Upgrade can be used to accelerate engines by rolling out unneeded cards for strong ones. This is especially the case for engines that need expensive parts in bulk, such as $5/$6 actions.
One great example is Upgrade’s direct interaction with Grand Market. Under normal circumstances, a Grand Market engine can be very difficult to get going, but Upgrade only requires a hand containing another copy of itself (or any $5 card) to snag you one. Ideally, the second Upgrade is not needed in your deck any longer, so you have no problem trashing one for a Grand Market. Furthermore, Upgrade trashes your Copper, thinning your deck to make the double Upgrade hand more likely.
In general, Upgrade can keep your deck rolling along. Bought an early Steward for trashing? You can make it a Caravan later. Already won Followers from the Tournament? Go ahead and make that Tournament that keeps getting blocked a Duchy near endgame. There are countless possible Upgrade interactions, but the key is to get the cards you need in your deck later on–if you stay focused on the now, you can end up with dead cards in your hand.
To illustrate, imagine a game where I open with Smithy/Silver on a board with no Villages in an attempt to get some $5 and $6 cards early, then transition in to an engine using Grand Market. Normally, this wouldn’t be feasible, but Upgrade makes such a thing possible. The only catch is, at least in a Kingdom with no Village cards, the Smithy will eventually be drawing actions dead, which doesn’t help me. Thus, the Smithy I bought early on makes a prime candidate for Upgrade. I can Upgrade the Smithy into another Upgrade, which will in turn increase my chance of getting more Grand Markets. It’s a little scary to trash your action cards, but it’s also important to envision your deck’s goal. Sometimes a card is only helpful to you during certain phases of the game. However, as with all cards in Dominion, you must use your discretion. It can be better to hang on to that Ambassador for a while before making it a Conspirator. You should probably reconsider Upgrading a cheap card if it is still fulfilling its purpose.
In short, Upgrade is a card that’s all about transitioning. Changing from one card to another, one strategy to another. It’s a powerful card that gives you something new and gets rid of something old, and it is also non-terminal, meaning you can keep playing Upgrades or any other card you need to afterwards. Even if you aren’t gaining anything particularly good on the Action end, trashing an Upgrade for a Gold will often benefit an engine. Few cards are as potent at engine building as this one.
Removing $0 cards, Estates, and Silver
Unless Poor House is in the Kingdom, Upgrade is a good Copper trasher. If you have nothing significant to gain from Upgrading another card this turn, removing a Copper will at the very least reduce your deck’s size by 1. Upgrade can also trash Curses, which is always nice. Upgrade performs better with fewer cards in the deck, so even though I stressed that the card is at its best upgrading expensive cards, that doesn’t mean this ability should be ignored. Sometimes Upgrade’s the only method of Copper trashing available, and it makes a pretty good one since it can be used later on too.
Upgrade loves to have good $3 parts in play (though it doesn’t care about those too much if you’re playing with Shelters). The ability to make starting Estates in to long-term useful cards like Fishing Village and Menagerie must not be ignored, and contributes to making Upgrade a good opening card on 5/2 and a good pickup in the first reshuffle.
Trashing Silver for important $4 cost Action cards can also be an important strategy. Conspirator, Vineyard, and Scrying Pool decks come to mind; these decks benefit more from having extra actions than having a Silver.
Upgrade is fantastic for ending the game on three piles, and some of the most skillful uses of the card involve doing so. Again, the Upgrade / Grand Market interaction makes a nice example. In that scenario, you’ll have few problems purchasing all the Upgrades (probably with the help of your opponent), which will then make it simple to empty Grand Markets. (Furthermore, Grand Markets make it easy to run out the Estates or other $2 piles) As with any pile out strategy, do be wary of your opponent’s actions. You only want to end a game early on a win, so if he’s running a fast strategy like Embassy/Big Money, be mindful of the score before getting any wise ideas. Note that you can also leave a pile at 2 or 3 cards your opponent cannot easily run out, then pounce on them at a later time.
The Upgrade trap
Many novices (totally not me when I first saw it, nope) will see Upgrade’s effect and think they can easily just keep Upgrading the same cards, eventually getting up to a Province. While theoretically this seems nice, the simple fact of the matter is it’s one of the slowest ways to play Upgrade (Upgrade is a deck accelerator, not a slog card, remember) and this strategy rarely ever works. You don’t want to focus on doing such a thing, and a better option is actually to BUY expensive cards and THEN Upgrade them. To spell it out more plainly, why spend up to six turns (which you can’t even guarantee lining up) Upgrading Estate -> Silver -> Militia -> Upgrade -> Grand Market -> Forge -> Province when you could just buy one of the last three and get your Province faster? Remember, six turns is a lot of time in a game of Dominion, and while you may be able to pull this off once, you usually need more than one Province to win. I think that it’s better to consider Upgrade a setup card than a finisher.
$7 -> Province (and similar)
That said, it’s viable to upgrade $7 cards to Provinces, or even Provinces to Platinum if you’re bold and sure it won’t backfire (Even in a Colony game, losing six points could matter). However, if you cannot accomplish this quickly, there are probably better ways to get the cards you need. Schemes can be used to set up such a scenario (top-deck Upgrade and a $7 action card), but Scheme is one of only a few cards that can.
In the late game, odds are you don’t mind losing a Forge, which you probably would have used to gain a Province anyway. Many $4 cost cards are also better to change to Duchies when things are coming to a close. The only bummer is that you can’t gain a Colony in this way without lots of cost reduction cards (and if you had enough of those, you were probably winning the game anyway).
When not to Upgrade
Upgrade is a strong card for setting up engines, but there are some cases where you should probably avoid it. The first is in any sort of Big Money deck. These decks rely on just a few actions and many treasure cards. The problem for Upgrade is that treasure costs go up in increments of $3, so you won’t be able to get the cards that a Big Money deck needs the most. Besides, those decks often don’t mind hanging on to Copper and Silver in the late game.
If you already possess cheaper cards serving the same purpose (Remake being a great example), the opportunity cost on Upgrade may be too great. Upgrade can still be useful in tandem with other upgrading cards, but if you only need one, you can often pass.
The other reason to avoid Upgrade is if there are no good upgrades to be made. For instance, if there are lots of good $4 actions in the Kingdom but no $5 actions you want, all you’re getting out of Upgrade are Duchies and Gold (if you get multiple Upgrades) unless there is a $3 -> $4 transition you want. However, that price point tends to be more trivial than the jump from $4 -> $5. Use your discretion, though.
A third reason to avoid Upgrade is against handsize reduction attacks. With only 3 cards in hand after a Militia, playing an Upgrade can sometimes leave you with uncomfortable choices as to what to trash.
Upgrade is highly interactive with other cards, but I’ll mention a few cases to keep in mind.
While you have to trash cards when you Upgrade them, have a party when playing Possession on your opponents. You can turn those Duchies in to Golds at no point penalty, get useful engine parts for trashing something you didn’t want to lose from your own deck, and so on. You can also trash Provinces or Colonies if you need all of the other cards in hand.
Scrying Pool decks love Upgrade! Ditch Coppers, turn Estates in to useful action cards, get rid of Silvers you no longer need, eventually ditch the Potion… the possibilities are endless, and it’s one of the deck archetypes that benefits the most from Upgrade. Remember, decks that want lots of actions want their actions to stay relevant.
Festival/Library or other Disappearing Hand engines
These types of engines sometimes suffer from being unable to afford their parts quickly enough. Upgrade helps out by eliminating some of the needed $5 buys and replacing them with $4 buys. You could pick up some intermediary card on a $4 hand such as Caravan, then Upgrade it to a Festival. Removing Coppers and Estates also greatly benefits these engines, and Upgrade even reduces the hand size on play. It’s a win-win.
Moneylender and other trashers with diminishing returns
Many trashers run out of steam after you have eliminated the cards they want to trash. Upgrade, naturally, combos very nicely with them. Moneylender is a particularly good case because it can also become an Upgrade or even a Duchy (which might be helpful by the time it runs out of Copper). Upgrade also helps to remove Copper, accelerating you to the point where Moneylender is no longer useful.
Are all the Curses or Ruins out? Why don’t you turn that lovely Sea Hag in to something more useful now? Incidentally, Upgrade also helps trash any Curses you received along the way.
Cards that want variety
Menagerie probably gets the biggest boost from Upgrade out of the variety-based cards. Why? Well, you can trash cards from the hand to set up a Menagerie’s secondary effect, and you can remove cards you have several duplicates of at the same time. Otherwise, Upgrade is a fairly obvious way to get multiple types of cards without having to expend many buys. In Fairgrounds Kingdoms, it’s often difficult to get 15 or more types of cards and also keep up an economy, but Upgrade helps to pull that off. Estates can become $3 cards, extra Silvers can become $4 cards, and so on. Upgrade can also Upgrade a copy of itself in to a Fairgrounds, which has the added benefit of not removing a card type from your deck.
Gain a $5 card and get the Fortress right back to be Upgraded again? Yes, please! This trick can be used to pile out fast or just to gain lots of powerful cards (Wharf/Upgrade/Fortress is pure dynamite). Not much else needs to be said about this combo.
On-Trash Effect cards
Upgrade makes a great enabler for many Dark Ages trash effect cards as it trashes through a trimmed deck. In other words, the likelihood of triggering one of these effects is pretty high. Rats and Market Square are particularly good, the first for drawing cards while gaining $5 cards (one of the few Rats combos that seems immediately powerful) and the second for trashing junk and replacing it with Gold.
Poor House has the sometimes unfortunate effect of making the $1 Upgrade on Copper less effective, as it no longer thins the deck. However, should you have the Villages and draw power to make a Poor House engine acceptable, Upgrade is an excellent enabler. It removes Copper from the hand and deck, and then (unlike Remake) allows another action, giving you the benefit from a Poor House in hand immediately.
Sometimes you just want to play Upgrade a few times, then get rid of it. Procession allows this with no hassle, and can even be good if there are no $6 actions available, assuming you just wanted to be rid of the Upgrade to begin with.
On-Gain Effect cards
Upgrading in to an on-gain effect has the benefit of the cards being available on the same turn, should you be able to draw them afterwards. An example case: Upgrade an Upgrade in to a Border Village and Witch, play a Smithy, reshuffle and draw the Border Village and Witch. That’s a case of perfect shuffle luck, but scenarios like it can be set up in some cases.
This is more of a fun combo than a helpful one, though it can certainly be powerful if the Kingdom can actually set it up. Playing multiple Highways or Bridges will allow you to Upgrade cheap cards in to very expensive ones. After four Highways, any card cheaper than a Duchy can become one. After seven, you can gain Provinces out of just about anything. If you’re pursuing this strategy, watch how many Highways you play–playing eight means you won’t be able to green, and you will lose the ability to trash $0 cost cards after a single Highway. Note that in order to pull such a thing off, you will likely need heavy card draw (Tactician, Alchemist, Wharf, King’s Court, Menagerie, etc…) and a faster trasher than Upgrade in play. Nonetheless, it’s a fun interaction to consider.
Watchtower combos with everything and Upgrade is no exception. In fact, Watchtower likes Upgrade a whole lot, especially with Village support. Why? Well, you can trash a card (let’s say Estate), gain a useful upgraded card such as Fishing Village, top-deck the card with Watchtower, then even play Watchtower and draw the new card. Drawing with the Watchtower is especially beneficial since Upgrade reduced the hand size. This is useful early in the game when you need to keep cycling and still good later on when you need lots of money–trashing a $5 card for Gold you can immediately use is nothing to sneeze at.
Countering Junking Attacks (Saboteur, Ambassador, Swindler)
Upgrade, while not a hard counter to these types of attacks, helps mitigate their effectiveness. When an opponent forces you to take a card you do not want, Upgrade can make it something better (or even remove it altogether). Sadly, you still lose the card that got junked in the case of Saboteur or Swindler. In the case of Swindler, do be aware that Upgrade can be Swindled in to a Duchy, which is downright painful early on in a game.