Slay the Spire is a deck-building game. Each character starts with a deck comprised of strikes, defends, and some unique cards as well as a character-specific starter relic. Each floor you ascend within the Spire will see you deal with challenges that change with every run. When you first play the game, you are restricted to Ironclad, with each subsequent character being unlocked by playing as the previous character.

Ironclad's color is red. Ironclad's world is relatively binary compared to the other characters: deal damage and block damage. Ironclad treats HP as a resource, as he heals after every combat and has several cards that can either increase or decrease his HP in exchange for other effects. Ironclad also has synergy with exhausting cards, which makes removing cards not quite as necessary. Ironclad is usually much more pressed for energy than the other characters, who have more 0-energy cards and ways to acquire energy or deal damage/generate block without it. This is especially an issue with Ironclad's powers, as they're generally more expensive than the rest.

Silent's color is green. Silent generally relies on shivs and/or poison, but there are runs where she may rely upon neither. She has more 0-energy cards and ways to keep her deck moving than Ironclad. Rather than exhausting cards like Ironclad, her deck is all about drawing and discarding cards.

Defect's color is blue. Defect's wrinkle is his orbs. Orbs make it so no turn is a waste, as they have various effects they carry out before turns begin or after turns end along with the possibility of being evoked. Like Silent, Defect has many 0-energy cards. For Defect, the important thing is to understand what the orbs are doing and what orbs you need out. If you need block, prioritize frost orbs. If you need damage, prioritize lightning orbs. Note that dark orbs also deal damage, but only come in handy if you can evoke them, meaning you need to keep your orb generation moving to make dark orbs useful. Lastly is the best orb, plasma, which you want to safeguard if you generate it, meaning if you are to evoke it, make sure you put that energy to use.

Watcher's color is purple. Watcher has stances. Wrath deals and takes double damage, Calm generates energy when you leave it, and Divinity deals triple damage and generates energy when you enter it. The generally accepted method to playing Watcher is called stance dancing, which involves changing between the Wrath and Calm stances as often as possible. In general, you do not want to end a turn in Wrath stance due to taking double damage, but it's okay to stay in this stance if the enemy isn't attacking or if you have enough block. Conversely, finishing a turn in Calm stance if you don't need the energy that turn is best as you're effectively banking energy for next turn. Watcher's deck has many retained cards, so keep the hand limit of 10 in mind, as you may sometimes need to use cards just to prevent them from limiting your card draw. Some Watcher cards also have the Scry ability, which lets you look ahead and discard upcoming cards in your draw pile.

In terms of offensive to defensive, the order goes Watcher, Ironclad, Silent, then Defect.

In terms of energy availability from most energy to energy starved, the order goes Watcher, Defect, Silent, then Ironclad.

For most deck-building strategies, you want your deck size as small as possible. Watcher benefits the most from a small deck. Ironclad's reliance on exhaust and Silent's reliance on draw and discard help them manage larger decks. Defect has several more nuanced cards that deal with larger decks, such as Hologram and FTL. Note that while these three characters all have ways to deal with larger decks, if you don't find their deck management cards but have been adding cards throughout the run you may find yourself in trouble.

To shrink your deck, for Ironclad/Silent/Defect get rid of strikes and then defends whenever possible while for Watcher you want to do the opposite and remove defends first. If you have cards that exhaust other cards and don't have any curses to use them on, removing these isn't as critical but still good to do if you can. Also, if you find yourself with many block cards but not many attack cards, you can violate this rule and remove a Defend instead.

This also means avoiding curses when you can, as they gum up your deck among their other negative effects. If you end up with a curse, it takes top removal priority, so note that it can make sense to accept a curse if the benefit is good enough and a shop is coming up. If you have reliable exhaust capabilities then it can also be okay accepting a curse.

Because of this way of thinking, most colorless cards are actually a waste of gold, as they clutter your deck. Colorless cards worth considering are ones that involve card draw, cost 0 energy/invoke playing cards for 0 energy, or "Apotheosis" as their effects are good enough to ignore the trade-off. I mention Apotheosis because once it's in your deck, upgrading cards becomes much less of a priority and you can instead use campfires to rest or skip them entirely.

Your card choices can also be affected by the artifacts you come across. For example if you have artifacts that limit your card plays, card draw and extra energy isn't as valuable. If you have artifacts that provide additional energy, you don't need cards that provide extra energy as much. If you have artifacts that want you to play certain cards, either in one turn or over time, those cards gain additional value. An example of this would be Orange Pellets, which tasks you with playing an attack, skill, and power in one turn to receive its effect.

A trap players often fall into is planning ahead with their deck. What I mean by this is taking cards that may be useful later but currently are not. This can make it very difficult to pass Act 1 and can hurt you further if the cards you need to complete your deck don't appear.

For Ironclad, an example of this is Heavy Blade, a card that is useful if you already have ways to acquire strength but sub-optimal if you have no strength. Limit Break is another example of this, where it is completely worthless without strength so it effectively acts like a dead card. Because of this, there are times where the best choice is taking none of the cards being offered.

For Silent, an example would be Catalyst, as it's only useful if you have ways to apply poison. When I was new I took this when I saw it because I thought it would come in handy. I proceeded to not see any poison cards for most of the run.

To expand upon this, do not start a run thinking you'll be playing a certain type of deck, like a strength deck, a poison deck, etc. There will be runs where you see zero cards for your chosen deck type, and by the time you realize it you'll have skipped too many card rewards to build a winning deck.

The chance of seeing a rare card in the rewards increases each time combat occurs and a rare card isn't seen. Each card reward generated is affected by and affects the counter, meaning the chance of seeing a rare card increases between the first and last reward card you see after combat assuming the first and second cards aren't rare. This hidden counter resets when a rare card is seen. This hidden counter also affects shop cards, but seeing a rare card in the shop does not reset the counter.

Bosses drop only rare cards. Elites are more likely then regular enemies to drop rare and uncommon cards.

Upgraded cards won't drop in Act 1 (without a relic), but can drop throughout the rest of the run.

The chance of seeing a potion in the rewards is set to 40% at the start of each Act. When a potion drops, the chance drops 10%. When a potion doesn't drop, the chance increases 10%. Keep this in mind: if you haven't had a potion drop in a while and all of your potion slots are occupied, consider using a potion as you're likely to receive one at the end of combat.

Some potions can be used outside of battle, use this to your advantage if you need to clear a potion slot.

The order in which relics appear is randomized in each run. Whenever you see a relic and don't take it, it is returned to the bottom of the relic pool and will not be seen again until every other relic of its type is seen.

After defeating a boss, you are provided a choice of three boss relics. Some boss relics are class-specific, and every class has a boss relic that replaces their starter relic. A unique feature of some boss relics is they have both an upside and a downside. No other relics in the game can both help and hurt you.

The rightmost relic in the shop is from a pool of shop-exclusive relics. These relics can only help you.

Some relics can only be found by completing events. These relics can have either upsides or downsides, but not both (except Necronomicon). Oftentimes obtaining a beneficial relic from an event means paying a price of either HP, Max HP, a potion, a card, or gold.

The remaining relics are either common, uncommon, or rare. Some of these relics are class-specific. These relics can be found by defeating elites or opening chests. Chests come in three sizes, with the probability of receiving an uncommon or rare relic increasing as the chest's size increases. These relics can only help you.

After reading this guide, you should have an understanding for the game's framework. Please continue to Part 2 of this guide to learn more about traversing the Spire and what a run of the game actually entails. The second part can be found here.