Ascension is Slay the Spire's difficulty ladder. Each level adds one modifier, every modifier stays on as you climb, and each of the four characters climbs separately. Most guides list the 20 modifiers and stop there. The more useful question is which of them actually change how you should play, because many are a few HP here and a few gold there, while a handful force a different way of drafting, pathing and spending potions.
This guide starts with all 20 levels and an honest impact rating for each, then covers the thresholds that matter, how your strategy has to change, tips for each character, and the numbers for Act 4 and the Corrupt Heart at high Ascension.
All 20 Ascension levels at a glance
Beat the Act 3 boss with a character to unlock Ascension 1 for that character. Every win at your highest level unlocks the next one. Losing never lowers your level, and a run that dies in Act 4 still counts, because you already beat Act 3.
| Level | What it adds | Impact | Why |
|---|---|---|---|
| A1 | About 60% more elites on the map | Medium | You choose your path, so this is as much an opportunity (relics) as a threat |
| A2 | Normal enemies deal more attack damage | Low | A point or two per hit, for example Jaw Worm's Chomp 11 to 12 |
| A3 | Elites deal more attack damage | Medium | Gremlin Nob's Rush 14 to 16, Lagavulin 18 to 20, Book of Stabbing 6 to 7 per stab |
| A4 | Bosses deal more attack damage | Medium | Slime Boss Slam 35 to 38, Hyper Beam 45 to 50, the Heart's Echo 40 to 45 |
| A5 | Heal 75% of missing HP after a boss instead of all of it | High | You start Acts 2 and 3 hurt, so every fight after a boss costs more |
| A6 | Start each run having lost 10% of your HP | Low | Your max HP is unchanged; the first Rest Site or Burning Blood covers it |
| A7 | Normal enemies have more HP; some gain more Block | Medium | Hallway fights last a turn longer, which adds up over an Act |
| A8 | Elites have more HP | Medium | Nemesis 185 to 200, Giant Head 500 to 520, Book of Stabbing up to 172 |
| A9 | Bosses have more HP; some gain more Block | Medium | Time Eater 456 to 480, Awakened One 300 to 320 per phase, the Heart 750 to 800 |
| A10 | Start with the curse Ascender's Bane | Low to medium | Unplayable and Ethereal: one dead draw per combat at most, but it can never be removed |
| A11 | One fewer potion slot (two instead of three) | High | Potions are your emergency answers, and you now hold fewer of them |
| A12 | Upgraded cards in rewards are half as common | Low | Act 2 drops from 25% to 12.5%, Act 3 from 50% to 25% |
| A13 | Bosses drop 25% less gold | Low | Roughly 25 gold less per Act 1 and Act 2 boss: about one less purchase per run |
| A14 | Lower max HP: Ironclad −5, others −4 | Medium to high | Permanent for the whole run, and it shrinks every 30% Rest heal too |
| A15 | Events have worse outcomes | Medium | More HP loss, less gold or fewer cards, and some events give a guaranteed curse |
| A16 | Shop prices are 10% higher | Low to medium | Less to buy, and card removal competes harder with relics |
| A17 | Normal enemies get harder movesets and abilities | High | Act 1 and Act 2 hallway fights start hurting decks that used to coast |
| A18 | Elites get harder movesets and abilities | Very high | Gremlin Nob, Book of Stabbing, Reptomancer and the Act 4 elites change patterns |
| A19 | Bosses get harder movesets and abilities | High | Every boss gets a stronger version of its gimmick; the Heart gets Invincible 200 and Beat of Death 2 |
| A20 | Two bosses at the end of Act 3 | Very high | You fight the boss shown on the map, then a different Act 3 boss straight away |
The penalties are cumulative. On A12 you also play with everything from A1 to A11. Each level also adds 5% to several score bonuses, up to +100% at A20. You can always pick any level you have already unlocked, and Custom Mode lets you play any level without it counting toward progress.
The thresholds that change how you play
A5 and A6: the HP economy tightens
Before A5, beating a boss heals you to full, so a sloppy Act 1 has no lasting cost. From A5 you heal 75% of your missing HP instead. Arrive at the Act 1 boss with 20 of 80 HP left and you leave it with 65, not 80, and that missing HP follows you into the hardest part of Act 2. A6 adds a small starting deficit (10% of your HP) but does not lower your max HP. Together they make HP a resource you have to manage across the whole run, not fight by fight.
A10: Ascender's Bane is smaller than its reputation
A10 is often called a wall, but the curse itself is mild. Ascender's Bane is Unplayable and Ethereal, so if it is in your hand at the end of your turn it Exhausts for the rest of that combat. It costs you at most one card slot per combat, and it is worst in two places: a turn-one hand where you needed every card, and a small, thin deck where it shows up more often. What makes it annoying is that it can never be removed: not at the shop, not by Neow, not by events. Plan your deck around one permanent dead card.
A11: two potion slots
You hold two potions instead of three (Potion Belt gives four instead of five). This changes more than it sounds. With two slots you cannot keep a "boss potion", an "elite potion" and a spare, so a full belt means the next potion drop is lost. Potions cost no Energy and do not count as playing a card, which makes them your cleanest answers to burst turns. From A11, use them in the fight where they matter now rather than saving them for a fight you may not reach.
A14: lower max HP
| Character | Max HP | Max HP from A14 | Rest heal (30%) from A14 |
|---|---|---|---|
| Ironclad | 80 | 75 | 22 |
| Defect | 75 | 71 | 21 |
| Watcher | 72 | 68 | 20 |
| Silent | 70 | 66 | 19 |
Four or five HP looks small, but it lowers the ceiling for every heal in the run, including Rest Sites. Combined with A5 and A6, the Silent at A14 starts around 60 HP and has no healing of her own. This is where taking an elite on half HP stops being a calculated risk and starts ending runs.
A15 and A16: a poorer run
A15 makes many events less generous and more punishing: more HP loss, smaller rewards and some guaranteed curses. For example, Council of Ghosts gives 3 Apparitions instead of 5 for the same 50% max HP cost. A16 raises every shop price by 10%, and A13 has already trimmed boss gold by 25%. The result is fewer purchases, so decide early whether a shop visit is for card removal or for a relic, because you will often afford only one.
A17 to A19: new behaviour, not just bigger numbers
These three levels change what enemies do. A17 affects normal enemies, A18 elites, A19 bosses. Some verified examples:
| Level | Enemy | What changes |
|---|---|---|
| A17 | Cultist | Gains 5 Ritual (Strength every turn) instead of 4 |
| A17 | Jaw Worm | Bellow gives 5 Strength and 9 Block |
| A17 | Looter | Steals 20 gold per hit instead of 15 |
| A17 | Byrds | Flying 4: you need four hits in one turn to ground each Byrd |
| A17 | Chosen | Opens with Hex instead of Poke |
| A18 | Gremlin Nob | Enrage 3 (3 Strength per Skill you play) and a fixed pattern: Skull Bash on turn 2, then Rush twice, repeated |
| A18 | Lagavulin | Siphon Soul takes 2 Strength and 2 Dexterity instead of 1 |
| A18 | Sentries | Bolt adds 3 Dazed instead of 2 |
| A18 | Book of Stabbing | Multi-Stab gains a hit even on turns it uses Single Stab |
| A18 | Gremlin Leader | Encourage gives all enemies 5 Strength and minions 10 Block |
| A18 | Giant Head | Starts It Is Time from turn 4 instead of turn 5 |
| A18 | Reptomancer | Summons 2 Daggers at a time |
| A19 | The Guardian | Mode Shift 40 and Sharp Hide 4 |
| A19 | Bronze Automaton | No longer stunned after Hyper Beam; it uses Boost instead |
| A19 | The Collector | Mega Debuff applies 5 Weak, 5 Vulnerable and 5 Frail |
| A19 | Awakened One | Curiosity gives 2 Strength per Power you play |
| A19 | Time Eater | Head Slam adds 2 Slimed, Ripple adds Frail, Haste also gives 32 Block |
| A19 | Donu and Deca | 3 Artifact each, and Deca's Square of Protection adds 3 Plated Armor |
A18 is the jump most players feel first, because Act 1 elites decide early runs. Gremlin Nob in particular now hits on a schedule you can read: Bellow on turn 1, Skull Bash (Vulnerable) on turn 2, then two Rushes. Your starting deck plus one or two strong attacks has to kill it before the Strength from Skills piles up.
A20: two Act 3 bosses
After the boss shown on the map (floor 50), you immediately fight a different Act 3 boss on floor 51. The second one is not shown on the map, so your Act 3 deck has to answer all three: a Power-heavy deck that beats Time Eater may still lose to the Awakened One's Curiosity, and a Shiv deck that beats the Awakened One is exactly what Time Eater punishes. With Act 4 unlocked, the extra floor pushes Act 4 to floors 53–56.
How your strategy has to change
| Area | Low Ascension habit | High Ascension habit |
|---|---|---|
| Frontloaded damage | Take some damage early, scale later | Two or three strong attacks before the first elite. A17–A18 Act 1 fights punish slow starts |
| Card picks | Take good cards when offered | Fewer greedy picks: every card must help the next elite, the Act boss, or both |
| Elite pathing | Fight every elite you can reach | Fight elites when HP and deck allow, with a Rest Site after. Burning (Emerald Key) elites are buffed further |
| Potions | Keep them for the boss | Use them in elites and dangerous hallways; two slots fill quickly |
| Rest Sites | Smith whenever possible | Rest more often before elites; Smith only when the next fights are safe |
| Boss preparation | Adapt during the fight | Know the A19 version of the boss on the map and draft for it from the start of the Act |
A7, A8, A17 and A18 make the fights you used to stall through cost 20 HP, so early card rewards should go to damage until the first elite is beaten. Ascender's Bane and pricier shops make a thin deck matter more, so skip freely from mid Act 1. Elites are still your main source of relics: take them when HP and deck are ready, with a Rest Site after. The burning elite that drops the Emerald Key is buffed further, with Strength equal to Act number + 1, 25% more max HP, Metallicize or Regenerate. And spend potions in elite fights: HP saved there carries to the Act boss, while a potion held for the boss may cost you the next drop.
Tips for each character at high Ascension
| Character | Strength at high Ascension | Weak point | What to prioritise |
|---|---|---|---|
| Ironclad | 75 HP and Burning Blood healing 6 after every fight, which offsets A5 and A14 | Starting deck is slow against A18 Gremlin Nob | Damage early; Flame Barrier and Disarm are excellent against the Heart |
| Silent | Weak and Strength reduction (Piercing Wail, Malaise) blunt multi-hit bosses and the Heart | Lowest HP (66) and the weakest Act 1 | Dash, Predator, Dagger Spray and Die Die Die before committing to Poison or Shivs |
| Defect | Frost Block scales with Focus; Lagavulin's Siphon Soul cannot lower Focus | Slow first Act; Spire Shield's Bash can remove Focus | Damage that also Channels (Ball Lightning, Cold Snap) early, Focus by Act 2 |
| Watcher | Highest burst damage and the strongest starting deck | Wrath doubles damage taken: the Heart's 45 Echo becomes 90 | Always hold a way out of Wrath; spread damage instead of overkilling capped enemies |
Two notes the table cannot hold. Burning Blood is worth more at high Ascension than anywhere else, so the Ironclad should not swap it at Neow. And for the Defect, Static Discharge (Channel Lightning when you take unblocked attack damage) triggers on each hit of the Heart's Blood Shots, while for the Watcher, Vault does not reset the Heart's Invincible cap for the extra turn.
Full archetypes and key cards for each character are in the character guide.
Act 4 and the Corrupt Heart at high Ascension
Act 4 unlocks after you beat the Act 3 boss with the Ironclad, the Silent and the Defect, and you reach it by collecting all three keys in one run (see the beginner guide for how). It is a fixed path: Rest Site, Merchant, Spire Shield and Spire Spear, then the Heart.
Spire Shield and Spire Spear
You start between the two and take 50% more damage from whichever one is behind you; targeting a card at the other one turns you around. From A3 Shield's Bash hits for 14 and Smash for 38, and Spear's Skewer becomes 10×4. From A8 they have 125 and 180 HP. From A18 both start with 2 Artifact, Smash grants 99 Block instead of Block equal to its damage, and Spear's Burn Strike puts its 2 Burns on top of your draw pile. Arrive with potions to spare; this fight is where many A20 Heart attempts actually end.
The Heart by Ascension level
| Base | A4+ | A9+ | A19+ | |
|---|---|---|---|---|
| HP | 750 | 750 | 800 | 800 |
| Blood Shots | 2×12 | 2×15 | 2×15 | 2×15 |
| Echo | 40 | 45 | 45 | 45 |
| Invincible (max HP lost per turn) | 300 | 300 | 300 | 200 |
| Beat of Death (damage per card you play) | 1 | 1 | 1 | 2 |
| Minimum turns to kill | 3 | 3 | 3 | 4 |
The pattern is fixed. Turn 1 is always Debilitate: 2 Vulnerable, 2 Weak and 2 Frail, plus a Dazed, Slimed, Wound, Burn and Void shuffled into your draw pile. Turns 2 and 3 are Blood Shots and Echo in random order. From turn 4, every third turn is a Buff: it clears Strength Down, gives 2 Strength, and adds 2 Artifact (first), +1 Beat of Death (second), Painful Stabs (third), 10 Strength (fourth) and 50 Strength (fifth onward).
At A19+ the minimum fight is four turns, so you always face the first Buff, and Beat of Death 2 punishes decks that play many cheap cards per turn. What helps:
-
1
Blunt Debilitate
Artifact cancels the debuffs in order, so 1 stack stops Vulnerable. Orange Pellets and Clockwork Souvenir from the shop are the most reliable answers. Ginger stops Weak and Turnip stops Frail.
-
2
Handle Beat of Death 2
Tungsten Rod or one After Image negates Beat of Death 1. At A19+ you need both, two After Images, or Intangible. Otherwise count each card you play as 2 damage to yourself.
-
3
Punish the multi-hits
Blood Shots hits 15 times at A4+. Thorns, Flame Barrier, Static Discharge and Self-Forming Clay trigger on every hit, and Weak or Strength reduction cuts every hit.
-
4
Time your Strength reduction
Do not play Piercing Wail or Dark Shackles on a Buff turn. The Buff clears Strength Down and the Heart gets the lost Strength back.
-
5
Deal exactly the cap
Damage beyond 200 per turn (300 below A19) is wasted. Spread burst over turns and kill before the fourth Buff adds 10 Strength.
For which relics carry this fight, see the relic tier list.
Common mistakes on the climb
- Treating A10 as the wall. Ascender's Bane is one dead card. The levels that actually end runs are A17–A19 and A20.
- Holding potions with two slots. From A11 a full belt wastes every potion that drops. Use them in elites.
- Skipping elites entirely. A1 gives you more of them for a reason. Without elite relics the A19 bosses outscale you.
- Taking elites on low HP. From A14 your max HP and every Rest heal are smaller. Rest first or route around.
- Drafting only for the boss on the map at A20. The second Act 3 boss is a surprise. Cover Powers (Awakened One), card spam (Time Eater) and Artifact plus scaling (Donu and Deca).
- Overkilling the Heart. Damage past Invincible is lost. Steady 200 per turn beats one 400 turn.
- Playing Strength reduction into the Heart's Buff. It hands the Heart free Strength.
- Jumping levels in Custom Mode to "practise" A20. It is useful for learning one fight, but progress only counts in normal runs, one win at a time.
Related guides
New players should start with the beginner guide, which covers elites, bosses and pathing in every Act. Builds for each character are in the character guide, boss relic choices in the relic tier list, and our overall verdict in the review.
★Honest Take: twenty small taxes and four real tests
Ascension is not twenty equal steps. Most levels are small taxes: a few HP on enemies, a little less gold, slightly fewer upgraded cards. You will barely notice A2, A6, A12 or A13. The real tests are fewer: A5 and A14 make HP a run-long resource, A11 forces you to use potions, A17 to A19 change what enemies do, and A20 asks one deck to beat two Act 3 bosses and then a Heart with a 200 damage cap. The weak part of the design is that the game explains none of this; the A17–A19 changes appear only as "harder movesets", and you learn the details by losing to them. The strong part is that every level rewards the same skills: lean decks, honest HP management and preparing for the boss before you meet it. If you are stuck, the fix is rarely a better card. It is usually one greedy elite, one held potion, or one draft that ignored the boss.
