Slay the Spire 2 Card Upgrade Priority Guide: What to Upgrade First

Why Upgrades Win Runs

Every campfire gives you a choice: heal or upgrade a card. New players almost always pick the heal. I get it. Watching your HP sit at 40% before an elite fight feels awful. But a stronger deck prevents damage in the first place. That upgraded Block card, that power that now costs zero energy? It compounds over every remaining fight. HP is a short-term bandage. Upgrades are permanent power.

For a full breakdown of core mechanics, check out the Beginners Guide.

Rest vs. Upgrade: The Decision Framework

The default answer at a campfire should be upgrade. Forging a card makes your deck stronger for every fight after this point. Resting heals roughly 30% of your max HP, which only matters until the next time you take a hit.

That said, there are clear moments to rest instead:

Your HP is below 40% and the next node is an elite or boss. You can’t play your upgraded cards if you’re dead.
You have no high-priority upgrade targets left. If the best option is bumping a Strike from 6 to 9 damage, just heal.
Act 3 in general. By this point, your deck is mostly built. The remaining fights are brutal, and you need the HP buffer more than marginal card improvements.

And the moments to always forge:

Act 1, almost every time. Your deck is raw. You have starter cards begging for upgrades. The enemies are still manageable. Forge aggressively.
You have a build-defining card that transforms on upgrade. More on this below, but cards like Limit Break or Armaments become completely different when upgraded. Never skip these.
You picked up a key power card this act. Powers stay in play the entire fight. Upgrading them early multiplies their value across dozens of combats.

Two Types of Upgrades (and Why It Matters)

Not all upgrades are equal. I think about them in two buckets.

Number Buffs

These add a bit of damage, a point of Block, or one extra stack of a debuff. They make a card better but don’t change how you play it. Strike going from 6 to 9 damage is a number buff. Footwork gaining one more Dexterity is a number buff. These upgrades are fine, but they should sit near the bottom of your priority list.

Function-Changing Upgrades

These are the upgrades that alter what a card actually does. They add new keywords, remove Exhaust, change targeting from single to all, or drop the energy cost to zero. These are the upgrades that warp your entire run.

Some standout examples:

Armaments — Unupgraded, it upgrades one card in your hand for the combat. Upgraded, it upgrades your entire hand. That’s a massive swing.
Limit Break (Ironclad) — Removes Exhaust, turning a one-shot Strength doubler into a repeatable engine piece. This single upgrade can carry an entire run.
Coolheaded (Defect) — Upgraded, it draws 2 cards instead of 1 while still channeling a Frost orb. Card draw on a defensive card is absurd.

Always ask yourself: does this upgrade change how I use this card, or just how much it does? Prioritize the former.

Top 5 Upgrade Priorities by Character

Ironclad

Limit Break — Removes Exhaust, turning a one-shot trick into a repeatable Strength engine. Top priority.
Bash — 3 Vulnerable instead of 2. Upgrade before your first elite.
Demon Form — 3 Strength per turn instead of 2. The extra point snowballs in boss fights.
Body Slam — Drops to 0 energy. Free triple-digit damage in Barricade decks.
Armaments — Upgrades your entire hand instead of one card.

Full Ironclad breakdowns in the Ironclad Builds Guide.

Silent

Neutralize — More damage and Weak at 0 cost. Upgrade first in almost every Silent run.
Noxious Fumes — 2 to 3 poison per turn. That 50% increase compounds every turn of every fight.
Adrenaline — Extra card draw on a free card. Card draw is the Silent’s lifeblood.
Blade Dance — More shivs per play. Each one triggers shiv synergy relics.
Footwork — 2 to 3 Dexterity. Adds up across every Block card for the rest of combat.

Silent strategies in the Silent Builds Guide.

Defect

Defragment — More Focus means every orb passively hits harder or blocks more. Best Defect upgrade, period.
Coolheaded — Draws 2 cards when upgraded. Frost orb plus card draw for 1 energy.
Capacitor — 3 orb slots instead of 2. Only worth it if you have Focus to back them up.
Glacier — Bigger Block numbers and 2 Frost orbs. Anchors your defensive engine.
AoE Lightning cards — Any card that makes Lightning orbs hit all enemies trivializes hallway fights. Upgrade these early if your build uses Lightning.

Full orb strategies in the Defect Builds Guide.

Regent

Stardust — Damage per Star jumps from 5 to 7. Multiplies across your entire Star pool.
Hidden Cache — More Stars on use. Star generation is the Regent’s bottleneck.
Child of the Stars — Block scales with Star count. Becomes a wall when upgraded.
Shining Strike — Cheap, reliable Star generation. Smooths out early turns.
Royal Guard — Better Block values shore up the Regent’s fragile early game.

More detail in the Regent Builds Guide.

Necrobinder

Soul Spark — Starter card goes from 6 to 9 damage and adds 1 Vulnerable. Mandatory before Act 1 elites.
Dirge — More Souls, more Block, more Osty HP. A three-for-one upgrade.
Capture Spirit — Higher Soul count feeds your entire engine faster.
No Escape — Doom build finisher. Applies 10 Doom plus 5 more per 10 stacks already there. Scaling gets absurd when upgraded.
Squeeze — Osty deals 25 base damage plus bonus per Osty attack in your deck. Win condition in summon builds.

Full Necrobinder strategies in the Necrobinder Builds Guide.

Cards You Should Almost Never Upgrade

Not every card deserves your campfire time. Here’s what to skip:

Strikes and Defends. They’re filler. You should be removing them, not investing in them. The only exception is if you literally have nothing else to upgrade in Act 1.
Cards you plan to remove. If a card is on your chopping block for the next shop, don’t waste an upgrade on it.
Flat number bumps on situational cards. A card that goes from 8 damage to 11 and only gets played in specific matchups? Pass. Your campfire is better spent on something you draw every fight.
Summon cards with minor stat increases. Some Necrobinder summon upgrades only bump HP values by a small margin. The payoff rarely justifies the opportunity cost.

Campfire Strategy by Act

Act 1 — Forge aggressively. Your starter cards are weak and your deck is small, so each upgrade represents a huge percentage improvement. I upgrade at almost every Act 1 campfire unless I’m below 30% HP heading into an elite. Bash, Neutralize, Soul Spark, Zap — whatever your character’s bread-and-butter card is, get it upgraded before the Act 1 boss.

Act 2 — Mix it up. Your deck is taking shape. You’ve probably picked up a power or a key synergy piece that needs upgrading. But the enemies hit harder now, so resting becomes more reasonable. I still lean toward forging if I have a high-priority target, but I rest more often here than in Act 1.

Act 3 — Rest more. Your deck should be mostly built. The fights are punishing, and incoming damage is high. Unless you just picked up a game-changing card that desperately needs its upgrade, take the heal. Surviving the boss matters more than squeezing out 2 extra damage per card.

Smith Relics That Change Everything

A few relics directly interact with your campfire decisions:

Miniature Tent — Rest AND smith at the same campfire. Removes the entire decision. Take it every time.
Fusion Hammer — +1 Energy but you can never smith again. Only worth it if your core cards are already upgraded. Taking this in Act 1 locks you out of 4-6 upgrades. I only grab it in Act 2 or later.
Peace Pipe — Remove a card at campfires instead of resting or smithing. Useful in thin-deck strategies, but don’t let it distract you from key upgrades.

Quick Reference: Upgrade Priority Checklist

When you hit a campfire, run through this list in order:

Do I have a card that changes function on upgrade? Forge it.
Do I have a key power card that’s still base level? Forge it.
Do I have a 0-cost upgrade that lets me cycle faster? Forge it.
Am I below 40% HP with a boss or elite next? Rest.
Is my best upgrade target just a small number bump? Rest.

Stick to this checklist and your win rate will climb. Upgrades compound over an entire run, and the players who forge smartly in Act 1 are the ones beating Ascension 20.