Game Breaker / Slay the Spire

Slay the Spire is a roguelike. And like with all others, what keeps players coming back is that euphoric feeling of stumbling into a high-roll — a run where everything goes right and they find absolutely broken synergies that completely tear apart the whole game. Some cards and relics in this game are undoubtedly better at facilitating these synergies compared to others. This page lists the most notorious out of them.

Cards

Ironclad:

• Corruption. Often regarded as one of the singular most powerful and impactful cards in the entire game, it's the driving force behind many game-winning decks. Once in play, Corruption discounts all Skills to 0 (even overriding cost randomization from things like Snecko Eye), at the "cost" of Exhausting them once played. Playing Corruption, although initially expensive, means that you don't have to spend any energy on Block for the rest of the fight, a luxury on a character as energy-hungry as the Ironclad. You can spend all of your energy attacking from that point forward, ensuring that all of your enemies are dead before you end up exhausting all of your defensive cards. Corruption becomes even more broken with Exhaust synergies such as Feel No Pain (which gives you extra Block per Exhausted card) and Dark Embrace (which allows you to draw a card every time you Exhaust a card). This combination is so powerful in drawing through your whole deck while nullifying incoming damage that it has been dubbed the "Exodia" of Ironclad's card pool. Still worried about your long-term blocking capabilities? Toss in a Barricade (which is now easier to get into play with Corruption, by the way, since you don't have to choose between it and blocking for the turn) and preserve all of the Block that you generate and ensure that no enemies can ever touch you.
  • Corruption by itself is already incredibly powerful, but add the similarly game-breaking Dead Branch relic and it literally becomes an automatic win. It takes luck to get this specific combo, but once you have it, the game basically runs itself. Dead Branch creates a new card every time you Exhaust a card (which will be any Skill with Corruption), that may themselves also be 0-cost Skills, and the cycle perpetuates until you have generated so much value that you could've won the fight several times over. Even the developers have joked about how overpowered this combo is.
• Feed. If the Ironclad kills an enemy with this card, he will permanently gain 3 or 4 maximum HP. With some care, you can line this up with kills on every floor and stack up so much HP that the sheer amount of it can be a win condition in the late-game all on its own. While it ordinarily Exhausts after use (meaning you can only Feed on one enemy per combat), you can play a Dual Wield on it to duplicate it for multi-enemy fights, or an Exhume to bring it back from the Exhaust pile, to repeat the process all over again. It's not uncommon for an Act 1 Feed to convert into an ending max. HP of 160 or more, enough to more than fully face-tank the first Heart cycle (thus ensuring that not even the worst possible draw order can bring you down), and if you get this as a Neow bonus, you're basically already 80% of the way to a win.
• Ironclad's Exhaust access can cause you to thin your deck down enough to enable infinites without having to rely on lucky card removes. The easiest method is by having more than one Dropkick in your hand, and an empty draw and discard pile, then simply playing the Dropkicks over and over (they will draw into each other infinitely) until the enemies are dead. There's also the infinite with two draw cards and a Sundial, etc.

Silent:

• The Silent's Rare pool has some of the absolute best cards in the game, including but not limited to:
  • Alchemize, which seems like a very unassuming card on the surface. All you do is brew a single potion. How could that possibly be as impactful as other flashy Rare cards that make you Intangible, double your damage, or destroy entire waves of enemies? The answer is simply that potions are really, really good, especially on higher Ascensions. Potions serve as risk mitigation to pad out bad draws on crucial fights (as you can use them at any time), and particularly strong ones can even push an otherwise weak deck to take a very aggressive path, allowing it to catch up to the curve. Alchemize is able to save a weak run by giving you strong resources to fight back until you find the synergies that you need, something that very few other cards are able to do. It can also still push good runs over the edge by generating broken potions such as Gambler's Brew or Silent's exclusive potion, Ghost in a Jar, which is possibly the best potion in the game. With how many times you'll get to play Alchemize in even a normal run, you're bound to find such potions eventually to save for an important endgame fight that can bail you out of a bad draw order or allow you to set up with impunity. And that's not even getting into its interactions with other strong cards such as Burst (which allows you to see 2 extra potions instead) or Nightmare (which duplicates the Alchemize and lets you "cycle" through random potions by discarding the ones you don't want and trying again). And if you have the Potion Belt relic or Sacred Bark? Hoo boy, let the fun begin.
  • Phantasmal Killer is a Skill that doubles Silent's damage output on the next turn after playing it. At first, you may think that this card is too unreliable, given that you're not guaranteed to see damage on the next turn. This goes doubly so if you're still fixated on Silent having only two "archetypes" to deal damage (Shivs and poison). Then you realize that Silent has the best upfront card draw and card manipulation in the entire game and can slot this on a discard + draw heavy deck to tear enemies to shreds by simply cycling into Eviscerates, Sneaky Strikes, or even Shivs over and over again.
  • Malaise, a Rare card that reduces the Strength of the target by X (or X+1) permanently, as well as applying Weak for the same number of turns. This card turns otherwise threatening encounters such as the Snake Plant, Book of Stabbing, and even the Time Eater into absolute jokes, completely shutting down their multi-hit damage and holding back their scaling. With a Burst, it could very well end up shutting them down for the entire battle. It can even block late Heart cycles with how much Strength it takes away. Everyone loves talking about how Shiv decks lose hard to Time Eater — well, Malaise nearly solves your defense in that fight in a single card, allowing you to set up your Accuracies and strike back with little fear, or even in desperate situations let you scale through your Shuriken/Kunai without letting the Time Eater scale up to any critical mass.
  • Wraith Form. This 3-cost Power gives you 2 or 3 turns of Intangible at the cost of sapping your Dexterity by 1 every turn afterward. Newer players fear this card, and there is still a vocal minority of experienced players who swear never to take it, but its power can't be underestimated. Intangible is just that good of a buff. Similar to Corruption, you can think of Wraith Form as taking care of your whole defense for those turns that you're Intangible, allowing you to focus on attacking. It can block some of the most threatening attacks in the game and excels in the Heart fight where it blocks a full cycle for you and, on Ascension 19 and 20, puts Beat of Death back to 1 damage per card instead of 2-3. And the Dexterity down debuff can be overcome using Artifact or Orange Pellets, holding it for the right time with Well-Laid Plans, or simply having a ton of Wraith Forms in your deck as your whole block plan, whether that's being fortunate enough to find multiple copies of it, or duplicating it with Nightmare for absolute silliness. Sure, playing multiple Wraith Forms will make you lose that much Dexterity per turn, but that's not much of a problem in most situations if you're Intangible for 6 or more turns in a row; pretty much the only attack that will pose much of a threat is the Heart's 12-hit attack, and that's only because your crippled Block cards will have a lot more difficulty blocking 12 damage than 1. There's rarely ever a time Wraith Form isn't at the very least a great option, except if your deck needs another solution to the Act 3 bosses (which are among the only fights that Wraith Form really struggles in).
  • After Image. Generating 1 Block per card played might not seem like a lot, but note that this is exactly how much you need to nullify the Corrupt Heart's Beat of Death below Ascension 19, and still helps when Beat of Death becomes 2 damage. And with Silent's ability to simply play a bunch of cards in one turn, whether that's through Shivs or simply drawing and discarding a ton of cards, it adds up quickly. It becomes absolutely broken in multiples — how would you like to block 2, or, if you duplicate the card with Nightmare, even 4 per card played? That's almost as much as a base Defend! And since it's not affected by Dexterity, it combos well with Wraith Form by allowing you to effectively shrug off the incoming Scratch Damage even if the fight's dragged on for a little while.
  • And of course, after reading all that, you may be clued in as to what the biggest enabler of all these cards is — it's Nightmare. Nearly every Rare card listed here is better in multiples, and Nightmare allows you to duplicate their already game-warping effects to play again and again. 3 turns of Intangible from Wraith Form now suddenly becomes up to 12, After Image is blocking for 4 per card, Malaise is literally preventing the enemy from playing the game... The list goes on and on. It doesn't even have to be on one of these cards! You're missing a block solution for one of the endgame bosses? Just Nightmare a Footwork, and now your block cards are in the double digits and you can easily deal with it. Not enough damage in the deck? Nightmare your Accuracy or Envenom to make your Shivs ridiculous, or Nightmare a Catalyst to turn that little poison you have into an unstoppable wrecking ball. Nightmare has a ridiculous ceiling and even outside of that, can provide an out to every fight so long as your deck has the option, making it well-deserving of its Game-Breaker status.

Defect:

• Echo Form is commonly considered to be one of the best cards in the game. It allows the first card you play every turn to play twice at no additional cost, making it easy to snowball with your Powers or deal extra damage. The only downside is that it's very costly at 3 energy, likely making you vulnerable on the turn you play it — and it's Ethereal unless it's upgraded, forcing you to use it or lose it — but given that you will either end the fight in a couple of turns or simply stop taking damage with that crucial double-play, it's hardly a point against it overall. Worth noting that Echo Form can also duplicate Self-Repair, which at the very least can heal back the damage that you take on the turn you play it, and at most can make you heal to full off every hallway encounter.
  • It's also worth noting that Echo Form can duplicate itself if you're lucky enough to get several copies, which stacks the effect. Apart from being a fantastic boon in a normal run, this can result in some ridiculously entertaining Endless Runs, and particularly if you combine cards from different classes, like it and Wraith Form ("My True Form", anyone?).
• Biased Cognition gives a huge burst of Focus to the Defect, at the cost of slowly losing it over future turns. Except that hallway encounters aren't going to last that long when your Lightning orbs are hitting that much harder. And Defect has an in-class way of overcoming that with Core Surge giving it Artifact to nullify the debuff. Said debuff can also be removed with Orange Pellets as well, allowing you to keep the extra Focus for the entire fight in both cases.
• Meteor Strike. A 5-energy card that deals a big chunk of damage and channels 3 Plasma. If you get this card into play, your energy is basically solved for the fight, and with Defect's strong card draw options the combat could very well soon be over. The hard part is, of course, getting it into play, but with energy generation from cards like Turbo and Aggregate, as well as ways to cheat it out with cards like Enlightenment and relics like Snecko Eye, it ultimately isn't as difficult to play as you might think. And if you have the Necronomicon relic or Echo Form in play, it immediately refunds itself and then some, allowing you to even continue the turn. The reward for playing Meteor Strike is so fight-warping that the best Spire players in the world will outright ignore the tried-and-true adage of "don't force a card/build" and take it even if they have no way to play it, knowing that the cost of carrying it as a dead card will be more than outweighed by the reward when they finally find that energy generator they're looking for.
• Seek, which is basically a tutor for any card in your deck, upgrading to let you pull any two cards you want from your deck. Turbo/Aggregate + Meteor Strike or Echo Form sure seems like a strong turn 1 play! Oh, what's that? Seek can get other copies of Seek? The setup potential of this card is absolutely incredible, and there's negligible drawback to picking it up other than opportunity cost if you see another broken card offered alongside it. It's one of the very best Bottled Lightning targets in the entire game.
• The Defect had some silly cards on its beta release that have since been reworked or removed:
  • Allocate, a Defect card, was considered so busted upon the character's beta release that it was removed from its card pool within a day, and that was after it had been nerfed twice before even then. It was a reusable Skill card that granted Focus (a stat strengthening most of the Defect's orbs) while lowering your Strength and Dexterity. Together with good orb generation, you could generate ridiculous amounts of block and/or damage with very little risk involved, hence the card's removal.
  • The Defect card Conserve Battery also got hit with the nerf hammer soon after the Defect came out of beta. Formerly, it gave a bite-sized version of the Ice Cream relic, carrying over energy from the current turn to the next, while available on only an uncommon card. Now, it only gives one energy to the next turn (and it's become a common card) — strong and technically "free" since it costs one energy to use in the first place, but nowhere near as strong and capable of fueling high cost Defect cards like Meteor Strike.

Watcher:

• Rushdown isn't the game's most powerful card per se, but it is the one that most warps players' strategies around itself. Drawing two cards when you enter Wrath stance seems harmless enough, but it's the only irreplaceable part of the game's easiest-to-achieve infinite combo. All you need is Rushdown, a one energy card that enters Wrath (such as the upgraded version of the starting card Eruption), a one energy card that enters Calm (such as Fear no Evil or Inner Peace), and an empty draw and discard pile. You can then endlessly cycle between Calm and Wrath, redrawing the same two cards, restoring the two energy they cost, and hitting an enemy for damage each time. Because this combo can be put together using only uncommon and starter cards and the deck is strong enough to win even if you never get offered the cards for the complete combo, "try to assemble the infinite combo every time" is one of the Watcher's easiest strategies and also one of its most consistent.
• Talk to the Hand is almost always a snap pick when you're offered it. It inflicts a debuff on an enemy that allows you to gain 2 (3 if upgraded) block whenever you attack it, which can generate an insane amount of block when coupled with cards like Flurry of Blows, Weave, or Tantrum. Watcher can sometimes generate so much block with such synergies that she doesn't even need to leave Wrath!
• Similarly, Mental Fortress is close to a snap pick every single time for the same reasons. It lets you gain 4 or 6 Block every time you change stances. Considering that stance-dancing is Watcher's most fundamental and powerful playstyle, you're bound to have a large selection of stance-changing cards at your disposal, and as such Mental Fortress can easily generate double-digit Block for you every single turn! It's absolutely busted in multiples or in conjunction with Talk to the Hand, and has the advantage in that it doesn't require you to strip the enemy's Artifact before you play it.
• Vault, which ends the current turn and lets you take another turn. This card is a godsend for setting up all the pieces of your combo, letting you quickly dig through your deck while playing your key cards along the way, and it Exhausts itself to get out of the way of any possible infinite. At the very least, it can let you tack on some additional damage and draw into a better hand. If you play it while Time Eater's clock would tick to 12, you will actually skip over the Time Eater's reset and can continue playing cards as if nothing happened!
• If you're not going in the infinite direction, Lesson Learned is absolutely ludicrous meta-scaling. If you kill an enemy with it, you will upgrade a random card in your deck. It's not too difficult to get lethal with Lesson Learned considering Watcher's Wrath stance makes it do 20 damage, and you will feel your deck grow in value more and more as you accumulate upgrades, so much so that you won't even need to Smith at campfires after a certain point! It's not uncommon for a deck with Lesson Learned to be fully upgraded by the time you step into Act 4 and have nothing left to do at the campfire before the shop.

Colorless/Special:

• Picture this all-too-common Spire scenario: You're not strong coming out of Act 1 and the Act 2 hallway encounters are kicking your ass. You're down to less than half your health with almost no block plan in your deck. But then you encounter the Council of Ghosts event, take the trade for Apparitions (which give you 1 Intangible on play), upgrade them at every campfire to remove their Ethereal, and then go on to win the entire run. Even better, if you come in with Toxic Egg, you won't even need to spend campfires on the Apparitions. In case you haven't noticed, Intangible is really good, even at the cost of some deck space and half of your maximum health. All you need to do is find card manipulation to get it into your hand at the right times, and nothing will be able to stop you. And if you find a way to duplicate the Apparitions or play them over again, that's even more of a bonus.
• Apotheosis is one of the best colorless cards, as it upgrades every card in your deck for the duration of combat, and when upgraded, costs only 1 energy, which can free up rest sites for HP recovery instead of upgrading cards. The only problem is that it's moderately expensive and not always in shops. Bonus points if you're lucky enough to select it with Bottled Lightning, meaning you can start every fight with it.
• Hand of Greed is up there with Apotheosis for being one of the very best colorless cards in the game. It deals a massive chunk of damage and rewards you by giving you Gold if you inflict lethal damage with it. And best of all, unlike other lethal triggers, it doesn't Exhaust after you use it. This means that theoretically, you could farm every enemy in a multi-enemy encounter for money if you stall enough, and the snowball effects that this can have on your run from being able to afford more removes, shop relics, and quality cards can't be understated.

Normal Relics

• Dead Branch, also known as "random bullshit go!" the relic, also known as the most absolutely broken, game-warping normal relic in the game, especially if you have the deck to fully exploit it (such as with Corruption, Shivs, or lots of energy generation). It has the simple effect of generating a new card every time you Exhaust a card. But wait, won't that clog your deck? Turns out that the benefits of seeing more options upfront outweighs the future drawback of having a slower later cycle — and keep in mind, this is all assuming the worst case, that the Dead Branch cards aren't good and that you don't want to play them when you draw them later. Frequently, the cards that it makes will be better than some of the things you have in your deck. And because of how card generation works, you are equally as likely to see a Rare card being generated as a Common card. Oh no, that Wraith Form, Echo Form, Barricade, or (god forbid) Corruption that the Dead Branch created is sure "clogging" my deck... This isn't even mentioning that the cards created can even extend your current turn by finding an energy generator, a draw card, or something else that Exhausts. Dead Branch provides so much upfront value that any "drawbacks" that it has are fully overshadowed by you literally just killing whatever is in front of you long before any of them can take effect. The only times when Dead Branch are bad is if you have Runic Pyramid (since you want to cycle out your hand every turn) or already have an infinite, where it would get in the way.
• Blue Candle is usually a Low-Tier Letdown, but has broken synergies that can make for some once-in-a-lifetime runs. The most notorious of these is its interaction with the Necronomicurse, a curse that will always return to your hand should you try to Exhaust it in any way. With the Tungsten Rod, you can play the Necronomicurse an infinite number of times without losing health, allowing you to fuel relics such as the Ink Bottle, or cards such as Feel No Pain to grant infinite Block or Dark Embrace to grant infinite draw. Without it, you can exploit the fact that you are paying 1 HP to attempt to Exhaust it, with relics such as the Runic Cube which will also allow you to draw infinite cards. And if you have the aforementioned Dead Branch…
• Pocketwatch, one of the absolute best early-game relics in the game that can still be useful even well into the late-game. It makes you draw 3 extra cards next turn if you played 3 or fewer cards this turn. Draw 3 is an absurd effect, much more so in Act 1 because you likely aren't playing more than 3 cards per turn ever, and essentially guarantees you find exactly what you need for that turn, only to repeat the cycle over again and do the same thing next turn. The effect is so strong that even in later acts, players will often intentionally float energy by playing only 3 cards so that they can dig through their deck faster. It's the ultimate early-game consistency machine that still holds value well into the run, and has absurd synergy with Snecko Eye, helping to pad out the lowrolls by providing more value on turns where the cost randomization screws you over.
• Any relic that increases the number of card rewards you get, such as Question Card or Prayer Wheel. These two relics have game-winning effects on their own; seeing any number of extra cards per combat increases the value of hallway fights by allowing more chances to find the perfect card to round out your deck. And when you combine the two of them, things get out of hand very quickly.
• Any defensive relic that can No-Sell an entire turn, including Fossilized Helix and Incense Burner. Skilled players can preserve the Buffer given by the Helix, or set up the Incense Burner on the best turns possible, to block the most dangerous hits in the game such as Bronze Automaton's Hyper Beam, Reptomancer's turn 2 flurry of daggers, and the Heart's first big attack. One free turn makes a world of difference in Slay the Spire, and can allow much more comfortable victories, which these two relics offer players time and time again, frequently cashing it at the end of a run with over 200 damage mitigated with proper play. They're that good.
• The Necronomicon itself is hideously busted in the right build. It makes any attack that costs two or more play hit twice, which includes heavy hitters like Bludgeon, Sunder, or Whirlwind. Very few enemies and only the lategame bosses can really survive 60 or more damage being dropped on them at once, and this is discounting certain strategies like holding a Windmill Strike for several turns.
• All three of the Egg relics — Molten Egg, Toxic Egg, and Frozen Egg. They make all cards you see of their type (Attack, Skill, and Power respectively) become upgraded. The earlier you see these relics in a run, the more value they will provide — they can even incentivize you to take extra cards even if your deck is already large, just because the value of a free upgrade is just that high. Seeing any one of these Eggs can be enough to snowball a run completely out of control from the very start.

Boss Relics

• Runic Pyramid, which is considered one of the best boss relics in the game, if not the best overall, and completely warps the strategy of the game around it. It allows you to keep your hand after every turn, which is essentially Silent's Well-Laid Plans (one of the best cards in her pool) on crack. Through this effect, if you have any game-winning two-card combo in your deck (such as Double Tap + a huge attack or Burst + Catalyst), or any card that is best timed for the right moment (like temporary Strength reduction), you are all but guaranteed to get it in play at the perfect time, because you can just hold the combo pieces until you have all of them. The only drawback of Pyramid is that if your deck still has a lot of basic cards like Strikes and Defends, they can get stuck in your hand, preventing you from drawing new cards. However, this downside is vastly overshadowed by the unparalleled consistency that the relic brings. The downside is also easily circumventable by taking energy generating cards, cards that Exhaust other cards, discard effects, or even taking an energy relic at any other point in the run.
• Snecko Eye, which is broken and strategy-warping in its own way. It allows you to draw 7 cards per turn instead of the usual 5, at the cost of becoming Confused at the start of the combat, which randomizes the cost of your cards. The extra draw is what makes this relic so powerful - if you have a key card that you need to play, you will see it much faster with Snecko Eye. The extra draw also offsets the drawbacks of Confusion, as the math works out so that you play an average of 3.5 cards per turn on 3 Energy. While there will be some turns where the cost randomization screws you over, the value and draw consistency that it provides in others makes up for the occasional lowrolls. Snecko Eye's cost randomization also means that you can now draft cards based on raw output. Cards like Meteor Strike become absolutely broken with Snecko Eye as it will always cost less than its original cost of 5, and cards like Sneaky Strike and Sunder that refund energy due to their high costs can actually become energy generators. Any draw cards become premium, as they can bring more low-cost cards into your hand. Defect's All For One becomes absolutely ludicrous because it will pull back any card that had its cost randomized to 0, and can form an infinite with itself or Hologram if both copies are discounted. And this isn't even mentioning that Ironclad's Corruption, which is already a game-breaker in itself, overrides the randomization, making Snecko Eye both essentially riskless as well as a fast way to get it into play.
  • Ironically, you never want to take Snecko Eye and Runic Pyramid at the same time. You want to cycle out the high cost cards that Snecko can roll, which Pyramid prevents, resulting in your hand getting stuck with high-cost basics that you can't get rid of. Individually, they're two of the most powerful relics in the game, but they should never be combined!
• Violet Lotus, one of Watcher's exclusive Boss relics, allows you to gain 3 Energy from exiting Calm instead of 2. This is one of the most broken effects in the game for how much Watcher has control over her Energy flow even without Violet Lotus. But with it, she goes energy-positive from her regular stance dancing shenanigans while still doing damage all the while, allowing for truly obscene turns. Pair this with any source of card draw such as Rushdown and watch enemies crumble to dust. It's also worth noting that Violet Lotus allows Watcher to use Vigilance as the Calm entry for her stance dance infinite, thus removing a card draft that you have to look for when trying to build towards it.
• As noted on the Low Tier Letdown page, Ring of the Serpent isn't very good on the PC release, because it isn't always a strict upgrade over the starting relic, and the opportunity cost to take it is high. However, on the mobile version, Ring of the Serpent becomes absolutely broken... because it literally is. Due to a bug, it draws 7 cards per turn instead of 6, which basically makes it into Snecko Eye with none of the downsides for a cheap deck, boosting the consistency of Silent to absurd levels.

Game Progression

• Want to beat the game easily and quickly get unlocks? Go to custom game and choose the options to bulk your deck to 50, get the hoarder option so that it triples the cards you earn, diverse to get more options, and also the option to get colourless cards. The card you want is Mind Blast. This card is innate, so you start with it in your opening deck each combat and it does damage based on your draw pile. This means each blast could do over 100 points of damage before the enemy has a chance to react. And if you upgrade Mind Blast, it only costs 1 energy to use. Also if you have the Snecko Eye relic and were able to buy more Mind Blasts then you could have a deck with a bunch of Mind Blasts costing 0 energy. A big Mind Blast opening deck can clear every fight in the 1st turn with perfect unless the enemy starts with some Thorns; kill 3 bosses perfect and you get the Beyond Perfect score.