📈 Slay the Spire 2 — Ascension Climbing Guide (A1 to A20)

Last updated: June 1, 2026 | Reading time: 10 minutes | For intermediate players

What Are Ascension Levels?

Ascension levels are Slay the Spire's difficulty scaling system. After beating the game with a character, you unlock Ascension 1 (A1) for that character. Beat A1, unlock A2. All the way up to A20 — where the game becomes brutally difficult. Each Ascension level adds one new modifier that makes the game harder, and these modifiers stack. By A20, you're playing with all 20 difficulty modifiers active simultaneously.

Climbing Ascensions is the core progression system for experienced players. It transforms Slay the Spire from "can I win?" to "how consistently can I win?" At low Ascensions, almost any strategy works. At high Ascensions, only tight, disciplined play succeeds. This guide covers what changes at each tier and how to adapt.

Low Ascension (A1-A5): Learning Fundamentals

A1-A5 is where you should focus on mastering the fundamentals. The modifiers at this level are relatively gentle:

• A1: More Elites spawn on the map. This is actually a buff in disguise — more elites mean more relics, more gold, and higher rare card drop chances. Experienced players find A1 easier than A0 because of the increased resource density.
• A2: Normal enemies are deadlier. Hallway fights hit slightly harder, which means you can't completely neglect block in Act 1 anymore.
• A3: Elites are deadlier. This is where elite hunting starts to require actual planning — you can't just face-tank Gremlin Nob and expect to survive.
• A4: Bosses are deadlier. Expect 10-20% more damage from Act bosses. Your scaling needs to come online faster.
• A5: Heal less after boss fights. Instead of healing to full, you recover 75% of missing HP. Sustain becomes more valuable.

Strategy for A1-A5: Focus on learning enemy attack patterns and experimenting with different builds. This is the time to try things — the punishment for mistakes is still relatively mild. Learn which cards are good and which are traps. Get comfortable with all four characters. The goal here isn't speed; it's building a deep understanding of card synergies and pathing decisions.

Mid Ascension (A6-A10): Tightening Your Play

A6-A10 is where the game stops pulling punches. You can no longer get away with sloppy play or greedy pathing:

• A6: Start each run damaged. You begin with 10% less max HP (or around 6-8 HP lost at the start). This makes early hallway fights scarier and Neow's blessing choices more important.
• A7: Normal enemies are tougher. More HP on hallway fights. You can't one-shot everything anymore — even Slimes survive an extra turn.
• A8: Elites are tougher. This is where elite hunting becomes genuinely dangerous. Lagavulin with extra HP is a run-ender if you're not prepared.
• A9: Bosses are tougher. Boss HP scales significantly. Your damage engine needs to sustain for longer fights.
• A10: Ascender's Bane — you start with an unplayable Curse card (Ascender's Bane) in your deck. This permanently pollutes your draw pile, making card removal even more valuable. The Curse cannot be removed and exhausts itself, but it takes up a draw slot.

Strategy for A6-A10: Card evaluation becomes stricter. You need to be more deliberate about what enters your deck. Ascender's Bane at A10 effectively gives you a 6-card starting hand instead of 5 — plan your first turn around drawing one dead card. Start thinking about "outs" — what specific cards or relics would solve your current deck's problems, and how can you maximize your chances of finding them?

High Ascension (A11-A16): The Real Game Begins

A11-A16 is where most players hit their first real wall. The modifiers at this level fundamentally change how you approach the game:

• A11: Lose 1 potion slot (down to 2). This is a massive change. Potions are life-saving resources, and having one fewer means you need to use them more judiciously. Don't save potions for "later" — use them before you lose HP.
• A12: Upgraded cards appear less often. Card rewards are less likely to offer upgraded versions, making campfire upgrades more important.
• A13: Bosses are much tougher. This compounds with A4, A9, and A14 — bosses now have significantly more HP and damage.
• A14: Lower max HP. You start with significantly less max HP (around 60-65 depending on character). Frontloaded damage in Act 1 becomes critical — you literally can't afford to take chip damage.
• A15: Unfavorable events. Many event rooms now have worse outcomes. Events that previously gave free relics might now cost HP. The "skip" option becomes correct more often. Risk/reward evaluation changes dramatically.
• A16: Shops are more expensive. Everything costs 10% more gold, and card removal costs 75→85 gold at minimum. Gold management and shop pathing become crucial skills.

Strategy for A11-A16: At this level, you can no longer afford to be "sort of" prepared for fights. You need to know exact enemy HP thresholds and damage numbers. For example, you should know that killing the rightmost Sentry in Act 1 takes exactly 38-42 damage. Use potions proactively — the reduced potion slot at A11 means you have less capacity, so a potion saved is often a potion wasted when you take unnecessary damage. At A15, treat most event rooms with suspicion; combat rooms become relatively more attractive because they're predictable.

Apex Ascension (A17-A20): Only the Best Decks Survive

Welcome to the deep end. A17-A20 is where Slay the Spire becomes a different game entirely:

• A17: Normal enemies have improved movesets and AI. Hallway fights that were trivial before now demand attention. The Act 2 avocado + mushroom fight becomes one of the scariest encounters in the game.
• A18: Elites have improved movesets. Gremlin Nob gains even more Strength per Skill played. Book of Stabbing starts with a higher base damage. Reptomancer's daggers have more HP. Elite hunting requires genuine preparation.
• A19: Bosses have improved movesets. Time Eater's card limit might drop to 10 instead of 12. Awakened One gains more Strength from Powers. Champion's execute hits harder. Boss fights demand specific preparation.
• A20: Double Act 3 boss. You must beat TWO Act 3 bosses in a row, with only a campfire between them. This is the ultimate test. Decks that "barely" beat the first boss will die to the second. You need a deck that's genuinely overpowered, not just adequate.

Strategy for A17-A20: At this level, consistency is everything. You need a deck that draws the right cards at the right time, every time. Card draw and deck manipulation become more important than raw power — a 40-damage Carnage is worthless if you draw it on a turn when you need to block 30. Study enemy attack patterns obsessively. At A20, plan for both possible Act 3 bosses. If you see Time Eater and Awakened One, prepare for the worst-case order (usually Awakened One first, then Time Eater with reduced card limit). Start every run with a plan, but stay flexible enough to pivot when the game gives you unexpected tools. Above all: accept that you will die. A lot. A20 win rates for even top players hover around 30-40%. Each death is data.

Character-Specific Ascension Tips

Ironclad: Burning Blood sustain becomes more valuable at high Ascension where every HP matters. Feed for max HP is premium. Exhaust engine (Corruption + Dark Embrace) is the most consistent A20 build because it turns your entire deck into a resource.

Silent: Wraith Form becomes S-tier at high Ascension — the Intangible turns let you ignore scaling enemy damage. Calculated Gamble + Tough Bandages is a reliable block engine. Poison scales safely; Shiv decks need Accuracy and After Image to compete.

Defect: Frost Focus is the most reliable A20 build. Glacier + Defragment + Biased Cognition (with artifact or Orange Pellets to strip the Focus loss) can out-block almost anything. Power-heavy decks are riskier because Awakened One punishes them.

Necrobinder: Still experimental at high Ascension. Bone Wall and Raise Skeleton seem to be the most consistent build path. Shadow sacrifice builds are high-variance — powerful when they work but unreliable. More data needed as Early Access continues.

The Mental Game

Climbing Ascensions is as much a mental challenge as a strategic one. Every failed run can feel like a waste of 30-60 minutes. But here's the truth: you cannot climb to A20 without losing hundreds of runs. The best players in the world lose more runs than they win. What separates them is how they process those losses. After every death, ask yourself: what was the point of no return? Was it a bad pathing decision in Act 1? A greedy card pick? An elite fight you should have skipped? Identify the actual cause of death — not just "I drew badly" but "I built a deck that dies to bad draws." Then adjust.

Take breaks between intense sessions. A20 runs demand full concentration. Your decision-making degrades after 2-3 hours. Come back fresh, and you'll make better choices. Good luck climbing — the Spire awaits.