Build Planner
Plan your deck with complete card database and AI analysis
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How to Use the Build Planner
The Slay the Spire 2 Build Planner helps you construct and evaluate your deck at any point in a run. Add the cards you currently have, include your relics, and get an instant score across five key metrics: Attack, Defense, Scaling, Consistency, and Synergy.
A good deck in Slay the Spire 2 needs a balance of all five. A deck that scores 90 on Attack but 20 on Defense will struggle against high-damage bosses. Use the scores to identify weak points and target your next picks accordingly.
Understanding the Five Metrics
Attack Score
Measures whether your deck has enough damage output. The ideal ratio is 30–50% attack cards. Too few and you can't kill enemies; too many and you have no defense or scaling.
Defense Score
Evaluates your block capacity. Skills that generate block should make up 20–40% of your deck. This score drops when you're too attack-heavy and can't survive boss damage.
Scaling Score
Power cards provide compounding value each turn — Strength, Barricade, Feel No Pain. A deck with 10–20% Powers has strong late-game potential. Too many powers and you stall in early turns.
Consistency Score
Based on deck size and average card cost. A 20–30 card deck with average cost 1.0–1.5 draws key cards reliably. Oversized decks with high-cost cards are inconsistent and will lose to bad draws.
Synergy Score
Accounts for relic interactions. Each relic you add boosts this score because relics in Slay the Spire 2 amplify specific playstyles. A deck with 3+ relics that complement your archetype is significantly stronger.
Deck Building Tips for STS2
- 1.Aim for 20–25 cards. Smaller decks cycle faster, meaning you see your best cards more often. Only add a card if it's better than your worst current card.
- 2.Commit to an archetype early. Mixing Strength scaling with Exhaust synergies dilutes both. Pick a direction by Act 1 and double down.
- 3.0-cost cards are underrated. Cards like Shiv, Leg Sweep, or 0-cost Strikes cycle through your deck faster and enable combo turns without spending energy.
- 4.One or two Power cards is usually enough. Powers are slow starters. More than 3 Powers in a 20-card deck means your first few turns are mostly setup with no damage output.
- 5.Upgrade your key cards first. Upgrading Bash, Shockwave, or your primary attack card first provides more value than spreading upgrades evenly.
Note: The Build Planner uses heuristic scoring — it\'s a strategic guide, not a guarantee. Always factor in your current floor, upcoming boss, and specific relic interactions when making decisions.
Frequently Asked Questions
How many cards should a good STS2 deck have?
Most winning decks in Slay the Spire 2 have between 20 and 28 cards. Smaller decks cycle faster — you see your key cards more often. Only add a card if it improves your worst card. The Build Planner penalizes decks over 35 cards for reduced consistency.
What is the ideal attack-to-skill ratio?
A balanced deck usually runs 30–50% attacks, 20–35% skills, and 10–20% powers. The exact ratio depends on your archetype — a block-heavy deck may run more skills, while an aggro deck skews toward attacks.
How does the Synergy score work?
The Synergy score increases as you add relics. Relics amplify specific playstyles and create passive value that raw card scores can't capture. A deck with 3+ synergistic relics is substantially stronger than the card scores alone suggest.
Should I add every rare card I find?
Not always. Rare cards are powerful on average, but a Rare that doesn't fit your archetype is weaker than an Uncommon that does. Use the Consistency score — if adding a 3-cost Rare drops it significantly, consider skipping.
Can I export my deck?
Yes — click the Export button to copy your full deck and relic list to the clipboard in plain text format, which you can paste into notes, Discord, or share with other players.