Is there an Act 4 in Slay the Spire 2? What actually ends a run
You kill the boss on floor 48, the health bar empties, and the run just ends. No key insert, no hidden door, no fourth act behind it. If you came here from the first Slay the Spire, this is the single biggest expectation to reset: in Slay the Spire 2 Early Access (v0.111 beta, September 2026) a run is three acts long. Act 1 rolls randomly between Overgrowth and Underdocks, each with its own enemies, events and boss pool. Act 2 is the Hive. Act 3 is Glory, and its boss on floor 48 is currently the last fight in the game.
The structure is fixed and fully mapped by the official wiki. Single-player bosses sit on floors 17, 33 and 48; multiplayer acts run one floor shorter, with bosses on 16, 31 and 45. After each of the first two bosses an Ancient heals you and offers a choice of three boons, which is where the old boss-relic draft went. After the third boss there is no Ancient and no next act. On Ascension 10 a second, different Act 3 boss appears on floor 49 and is fought immediately after the first, and that double gauntlet is currently the closest thing the game has to a fourth-act finale.
What does not exist is gating. In the first game, Act 4 required beating the Act 3 boss with three different characters and collecting the ruby, sapphire and emerald keys across runs before the door opened. Nothing analogous exists in STS2 as of v0.111: the official wiki's act and boss pages list nothing beyond Glory, and no key, flame or shard item appears in any reward table the community has documented. The run you start is the run everyone gets, first win or five hundredth.
One caveat about the moment after the kill. Community documentation describes a scripted story beat following the Act 3 boss (an Architect scene rather than a fight), which is community-reported rather than something Mega Crit has detailed in patch notes, so treat the exact staging as subject to change.
As for what is coming: the August 2026 developer newsletter confirmed a slower patch cadence while the team works on larger drops, naming an alternate Act 2 and a new character among them. The tracked roadmap also includes further alternate acts, new modes and a true story ending at the 1.0 release. Until then, endgame content lives at exactly two altitudes: floor 48 for everyone, and floors 48 plus 49 for Ascension 10 climbers. Everything in this guide is aimed at making you win those fights, not at speculating past them.
Why the Act 4 question keeps coming up: the Corrupt Heart shadow
The confusion is earned, because in the first Slay the Spire beating Act 3 was only half the game. The true finale was Act 4, The Ending: three fixed encounters capped by the Corrupt Heart, a boss that taxed every card you played and demanded a finished deck rather than a winning one. That design taught a generation of players that the third boss is a checkpoint and the real exam comes later. Search any STS2 thread about the end of a run and you will find someone asking where the Heart is within the first five replies.
The honest answer is that STS2 Early Access currently has only the first half of that equation. There is a final act and three final bosses, and there is no Heart. Mega Crit has not announced one, and the official wiki documents none. The ceiling of the game today is the Ascension 10 double boss, and if you want a long-term completionist goal in the style of the old A20 Heart clears, that is where it lives.
Community threads do nominate a candidate. Several players speculate that The Queen is being positioned as a future final boss, pointing at her binding debuff as the kind of mechanic you design for an endgame gate rather than a regular act boss. To be clear, that is speculation from Reddit, not a statement from Mega Crit, and nothing in the v0.111 files or patch notes confirms it. There is also an Act 4 Final Ascent mod on Nexus Mods; it is fan content that runs on the Steam Workshop support added in Major Update 2, not a beta branch of anything official.
Practically, the right mental model is to treat the floor 48 boss as your Heart. Every discipline STS1 players reserved for the fourth act travels forward: keep an answer card for the mechanic you cannot solve, spend potions instead of hoarding them, and know all three possible bosses well enough that no map roll surprises you. The difference is timing. Those skills are now stress-tested three fights earlier, with fewer floors of scaling behind you, which is why Glory kills so many runs that felt comfortable in the Hive.
One consolation for practice runs: Act 1 and Act 2 bosses pay 100 gold (75 on Ascension 3), a choice of three rare cards and sometimes a potion when they die. A run that dies at floor 48 has already been paid three times. Treat the loss as tuition and check what the winning line would have needed.
Your last boon: picking the Act 3 Ancient (Nonupeipe, Tanx, Vakuu or Darv)
The moment Glory loads, before you fight anything, an Ancient heals you (100 percent of missing HP, or 80 percent on Ascension 2) and offers three boons. This is the final draft pick of the run and the direct successor to the old boss-relic choice: Ancients replaced boss relics wholesale in STS2, and act-start boons are where that pressure now lives.
The Act 3 pool is Nonupeipe, Tanx or Vakuu, plus Darv, a merchant Ancient who can appear in either late act. Boon pools are documented by community guides as of mid-2026 and individual values move with balance patches, so read this as a menu sketch rather than gospel. Tanx is the blunt-instrument shelf: Sai grants 7 Block at the start of every turn, Throwing Axe replays the first card you play each combat, War Hammer upgrades 4 random cards whenever you kill an elite, and Meat Cleaver unlocks cooking at rest sites.
Vakuu carries the high-variance options. Fiddle draws 2 additional cards every turn but forbids drawing during your turn, which is a real hazard into The Queen, where mid-turn draw is your escape valve from Bound chains. Lord's Parasol obtains everything the merchant sells, absurd with saved gold. Jeweled Mask pulls a Power from your draw pile into your hand for free each combat (v0.111 changed it to pick a non-Innate power). Whispering Earring grants bonus energy but Vakuu plays your first turn for you.
Nonupeipe is the comfort pick: Signet Ring pays 999 gold on pickup, Brilliant Scarf makes the fifth card you play each turn free, Looming Fruit raises Max HP by 31, and Fur Coat marks 7 random combats in the act so their enemies have 1 HP, which converts the gauntlet before the boss into free pickups. Note that v0.111 nerfed her Beautiful Bracelet (Swift 3 on three chosen cards), so older tier lists overrate it.
Darv is where the STS1 boss relics went to retire: Empty Cage removes 2 cards, Pandora's Box transforms all Strikes and Defends, Black Star makes elites drop an extra relic, and the classic trade-off energy relics (Ectoplasm, Sozu, Philosopher's Stone, Velvet Choker, Snecko Eye, Runic Pyramid) all appear here with their old downsides attached. The decision rule for a finale is simple. Pick the boon that patches the boss you are weakest against, not the one that maximizes style. Flat block per turn covers Queen loops and Aeonglass Ebbs alike; a tempo boon does nothing at floor 48 if your block math is short.
The Queen: the 400 HP executioner and the 199 HP Amalgam clock
The Queen is a 400 HP boss (419 on Ascension 8) who walks in with an escort: the Torch Head Amalgam, 199 HP (211 on A8), carrying the Minion power. Her opening two turns are scripted. Turn one, Puppet Strings applies 3 Chains of Binding to every player: the first cards you draw each turn become Bound, only one Bound card can be played per turn, and cards un-bind at the end of the turn. Turn two, You're Mine applies 99 Frail, 99 Weak and 99 Vulnerable to all players. Those are functionally permanent: for the rest of the fight you deal 25 percent less attack damage, gain 25 percent less Block, and take 50 percent more from attacks. Every number below should be read as the debuffed reality.
The Bound rules reward precision. Because only the first cards drawn each turn get Bound, mid-turn draw effects like Acrobatics or Offering hand you unchained options, a community-documented interaction that makes extra draw the premier stat in this fight. Duplicates of Bound cards are also Bound, and Sly triggers or Duplicator tricks do not bypass the limit. Transforming a card mid-fight strips Bound off it, and Well Laid Plans can hold a Bound card for a cleaner turn.
While the Amalgam lives, the Queen does nothing but Burn Bright for Me: 1 Strength to the Amalgam, 20 Block to herself. The Amalgam runs a fixed loop of Strong Tackle 26 (32 on A9), Tackle 18 (22), Beam 8x3, then two Weak Tackles at 14 (16) each, repeating from Beam. Strong Tackle was added in v0.109 specifically to raise its front-loaded damage, so treat the opener as a real block check. The community-discovered timing rule: kill the Amalgam by turn 2 and she skips her first Enrage entirely, and if it dies off-turn, for example to Doom resolving at end of turn, she skips Enrage and opens with her attack loop directly.
Once the escort is dead she enters Enrage (+2 Strength) and cycles Off with Your Head (3 hits of 5, or 4 hits of 5 on A9), Execution (15, 18 on A9), Enrage. Factoring her Strength stacks and your permanent Vulnerable, the loop realistically reads around 7 damage x5 and 25 per cycle (9x5 and 30 on A9). That outpaces most flat block within a few cycles, so the fight is a race against her scaling. Bring Artifact charges for You're Mine (three separate debuffs means three charges to blank the turn), burst the Amalgam on your terms, and win through mid-turn draw. Design footnote: she is based on The Collector from STS1, and she plays like it.
Test Subject #C10: the 600 HP three-phase marathon
Test Subject is three bosses wearing one health bar: 100, then 200, then 300 HP (111, 212, 313 on Ascension 8), 600 total at baseline. The Adaptable power prevents death and triggers each revival, and a small wiki detail explains the name: it starts each save file as Test Subject #C8 and the number rises by 2 per kill, so #C10 is your second meeting with it.
Phase one alternates Bite for 20 (22 on A9) and Skull Bash for 14 plus 1 Vulnerable (16 on A9). The trap is Enrage 2 (3 on A9): it gains 2 Strength every time you play a Skill. Starter decks that lean on Defend-shaped cards hand it free scaling every single turn. The discipline here is playing fewer, better cards: attacks to race, and block concentrated into as few skill plays as possible. Strength-deck Ironclads and burst Regent lines handle this phase best.
Phase two revives with Painful Stabs and a single repeating move, Multi-Claw: 10 damage x3 (11 on A9), starting at 3 hits and gaining a hit every time it is used. Painful Stabs shuffles a Wound into your discard pile every time you take unblocked attack damage, and a growing multi-hit means many separate leak checks per turn. This phase is a perfect-block exam. Per-hit damage reduction and consistent Block matter more than one big armored number, and every point you leak converts into deck clutter that hurts your later draws.
Phase three swaps to Nemesis: at the end of every other turn it gains Intangible 1, so all damage it takes drops to 1. The move cycle is Lacerate 10x3 (11 on A9), Big Pounce 45, and Burning Growl, which shuffles 3 Burn into your discard and gives it 2 Strength (5 Burn and 3 Strength on A9). You must dump damage into the non-Intangible turns and arm Big Pounce turns with 45 Block. Multi-hit decks suffer here, since each hit is reduced to 1 during Intangible windows; concentrate damage instead.
Transitions wipe everything in both directions. Its Strength resets, but so do your debuffs and damage-over-time effects, and our enemy database flags that poison-style DoTs specifically reset between phases, so re-application is part of the fight plan. Between 0 HP and revival it is untargetable, though untargeted cards still resolve their other effects. Fatal triggers (Feed, Knockout Blow, Sunder) work in every phase, and with no reward screen after floor 48, timing those killing blows for the payoff is free value on the last boss of the run.
Aeonglass: racing the snowball at 512 HP
Aeonglass is the newest of the three finals and the purest mechanics check: 512 HP (535 on Ascension 8), no phases, and a three-move cycle that escalates forever. It opens with two powers, Withering Presence and Artifact 3. Withering Presence reads: every 6 cards you play, add a Wither to your hand. Wither is an Unplayable status that deals 3 damage at the end of your turn if it is still in hand (6 when upgraded). In other words, the fight charges you a toll for playing cards, and the toll gets worse the longer you take.
The cycle runs Ebb for 22 damage plus 33 Block (26 on A9), Eye Lasers for 11x2 (12x2 on A9), then Increasing Intensity. Increasing Intensity is the snowball: it shuffles a Wither+X into your discard pile (2 on A9), grants the boss 2+X Strength (3+X on A9), upgrades all Withers, and makes Withering Presence create Withers +X, where X is the number of times Increasing Intensity has been used. First cycle is a nuisance. By the third cycle its Strength and your Wither intake are both compounding, and by the fifth most decks are dead. The win condition is not surviving the loop, it is ending the fight before X outruns you, which makes Aeonglass the most tempo-sensitive final: front-loaded damage and efficient turns beat slow scaling engines here.
Because the Withers are the fight, exhaust and removal are the answers. Ironclad Stoke, Regent GUARDS!!! and Defect Flak Cannon clear multiple Withers while doing something useful, and the colorless card Purity exhausts up to 3 (5 when upgraded) Withers for any character. Discard effects like Prepared delay the end-of-turn damage for a turn, but the Withers come back on the next shuffle, so treat that as a bridge rather than a plan. Artifact 3 also matters on your side of the table: your first three debuff applications against it are negated, so do not open the fight by feeding it Vulnerable stacks that vanish.
The boss also has a churn history worth knowing when you read older guides. Aeonglass replaced Doormaker in v0.105 beta (May 2026), with Mega Crit stating Doormaker exceeded the intended complexity threshold for an Act 3 boss. It reached the main branch in Major Update 2 (v0.107.1, June 2026), was reworked twice more (v0.106 redesigned Wither, v0.107.0 moved its Block gain onto Ebb), and took a direct nerf in v0.109 that cut Ebb from 26 to 22 to lower front-loaded damage. All numbers above reflect v0.111 beta, and given the churn, expect drift.
The last five floors: planning for a boss you can see coming
Glory is fifteen floors (34 through 48) with five possible elites in the pool: Magi Knight at 82 HP, Flail Knight at 101, Spectral Knight at 93, Soul Nexus at 234, and Mecha Knight at 300, the last of which the community treats as a raid boss in its own right. Your boss is decided when the act generates, and the map tracks it, at Ascension 10 both icons, so there is no excuse for building blind. The single habit that separates consistent winners here is reading the boss icon at floor 34 and re-planning the remaining shops, rest sites and card picks around that specific fight.
The last shop deserves more respect than it usually gets. Shop relic prices were cut by 25 gold in Major Update 1 (v0.103.2), which quietly made the floor 44 to 46 merchant one of the best relic buys of any run, and on Ascension 6+ the removal service costs 100 gold for the first card and 50 more each time after. Decide between a relic, a removal and potions by asking what actually loses the boss fight: if the answer is a starter Strike clogging a Bound hand, remove; if it is 5 points of block per turn, buy the relic.
The rest site before floor 48 is a standard fixture, and the choice is matchup math, not vibes. Smith the card that changes the fight (the power that scales, the exhaust tool, the key upgrade) when one exists; otherwise rest, especially into The Queen, whose loop punishes every point of missing HP you carry. A Meat Cleaver from Tanx adds a Cook option here, and cooking Max HP into the finale is often the best rare line in the act.
Match your archetype to the door. Front-loaded burst and Strength lines want The Queen, because the Amalgam race is exactly their game. Poison and Doom decks also love her, since damage-over-time persists on both bodies and a Doom tick killing the Amalgam off-turn skips her first Enrage. The same decks must re-apply everything three times against Test Subject, whose phase transitions wipe DoTs. Multi-hit and claw decks need Test Subject discipline: dump damage only on non-Intangible turns in phase three. Exhaust-block decks are practically built for Aeonglass and for Test Subject phase two, where Wounds and Withers feed their engine.
Finally, walk in empty. Potions do not carry past the run, a Fairy in a Bottle is pure insurance, and Pantograph heals 25 at the start of every boss combat, which at Ascension 10 fires twice. The run ends at the kill; there is no act four to save for.
Ascension 10: the double boss finale that is currently the endgame
Ascension 10 replaces the ending of the run with a gauntlet: after the floor 48 boss dies, a second, different Act 3 boss appears on floor 49 and is fought immediately. The official wiki notes this is the one exception to the rule that bosses are preceded by a rest site. You get the reward screen for the first kill, then the second health bar loads with whatever you have left: your remaining HP, your potions, and your deck exactly as it stands.
The detail that reshapes deckbuilding is that scaling effects reset between the two fights, as documented by guide sites covering the mode. Powers, Strength stacks and fight-long setup do not carry over. Engine decks that need three turns to come online pay that setup cost twice in consecutive fights with no heal between, and one-shot burst decks that won fight one through a stacked combo start fight two from zero. The decks that win A10 are consistent ones: engines that re-establish in a turn or two, block that does not depend on long ramps, and enough raw damage to close two 400 to 600 HP health bars in a row. This is also why community advice keeps repeating a counterintuitive line about throttling deck speed. Greed that wins fight one by a mile can be greed that loses fight two by exactly that much.
Because both boss icons are visible on the map from the start of the act, A10 is a planning puzzle rather than a roulette. You are not answering one mechanic, you are answering a pair: Queen plus Aeonglass asks for an Amalgam burst plan and a Wither exhaust plan in the same fifteen cards of picks. Aeonglass plus Test Subject is an attrition gauntlet where tempo and re-applied damage both need homes. Pick the Act 3 Ancient boon that covers whichever of the two matchups your deck is weaker into, and treat the floor 44 to 46 shop as your last chance to buy the missing answer.
Pantograph is the community's favorite relic for the climb, and for once the popularity is pure math: 25 HP at the start of every boss combat means 50 HP across the finale, spent exactly where the run is decided. Opinion on the difficulty is genuinely split. Some players report A10 feels like a reward rather than a spike because by the time you unlock it your deck discipline is already there; others call the two-boss gauntlet absurd. Both are community-reported takes, and the disagreement itself tells you the level rewards preparation more than reflexes. The broader consensus, that STS2 at A10 is noticeably kinder than STS1 at A20, is also community-reported, but it matches the design: ten cumulative levels, one gauntlet at the end, and no Heart behind it.
After the win screen: what your first Glory clear actually unlocks
Your first Glory clear with a character does more than end a run. Defeating any Act 3 boss unlocks Ascension for that character, and every subsequent clear at a given Ascension level unlocks the next one. The tracks are per-character, so a maxed Ironclad tells you nothing about the Silent, and you can always drop back down to any level you have already unlocked, which matters more than it sounds: grinding unlock wins at A1 is a legitimate way to farm confidence while your fundamentals catch up.
Meta progression runs through the Timeline, which replaced the old per-character unlock trees with one shared track of story segments called Epochs, grouped into Magnum Opus, The Reopening and one block per character. Epochs open on cumulative milestones: total score thresholds that climb from 200 up past 30,000, your first finished run, finishing runs with specific characters, act clears, 15-elite and 15-boss kill counts per character, and Ascension 1 wins with individuals. Rewards typically land three items at a time, cards, relics or potions, while the bigger nodes grant whole characters, the Ancient Neow for new saves, events and modes. Two placeholder Epochs, Elsewhere and Somewhere, unlock nothing and are reserved for future content, which is as close to an official wink about the endgame as anything in the game files.
Mode unlocks hang off the same system. Beating Glory three times unlocks Custom Mode, and the Daily Run carries its own separate condition: the in-game text asks you to play a single run with all characters and beat Act 3, and community reports suggest the order matters, with the Act 3 clear only counting after every character has been played at least once (flag that as community-reported and check your own save). Neither dailies nor custom runs grant Epochs or achievements, so anything that moves the Timeline has to happen in normal runs.
Looking forward, the official picture is clear about direction and vague about dates. The Watcher is confirmed for Early Access with no release window. The August 2026 newsletter confirmed the team is working on an alternate Act 2 and a new character after slowing the patch cadence for bigger drops, and the roadmap community documentation points toward further alternate acts, new modes and a true story ending at 1.0. So the final boss question stays open by design. Today the title belongs to whichever of the three sits on your map. If the speculation about The Queen ever pays off, it may belong to her. At 1.0, the true ending gets to settle the argument, and every floor 48 clear you bank before then is practice for that fight.