Slay the Spire 2 bosses have probably caused you a lot of trouble. Ok I know that. So I prepared this complete boss guide and also the way to beat them, actually I show their weak points.
There are ten main bosses spread across three Acts. Act 1 splits into two separate paths which are Overgrowth and Underdocks. So you pick your route after the first few floors. Act 2 locks you into the Hive, and Act 3 closes out in Glory.
And if you wonder, there is no Act 4 yet. But the developers have announced that in the final version they’ll add a proper ending. So we can expect another Act or something.
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Act 1a: Overgrowth
As I mentioned earlier Act 1 actually has 2 routes. First, we look at the Overgrowth. It drops you into dense forest ruins where the bosses tend to be very aggressive.
These fights test whether your starting deck can handle early pressure without collapsing. Grab any block potions or relics that give steady damage ticks. Kunai, Shuriken, or even a simple Pen Nib pays off fast. Thin the deck aggressively so you cycle into answers before the boss’s ramp. Most runs here end in six to eight turns if you play tight.
Ceremonial Beast
Ceremonial Beast is a massive horned creature that stacks strength every other turn and loves to lock you down once its health gets low.
The two mechanics that define the fight are Plow (a big strength buff plus a stun if you drop it below 150 HP) and Ringing (forces you to play only one card that turn).
How to Beat Ceremonial?
Bring the beast to 160 HP without triggering the low health stun (Try not to activate Plow). Then unload everything on turn 3 while its strength is still manageable. Save a solid block for the Ringing turn so you can still defend with that single card. Poison or burn relics chip away during the setup turns. Ironclad players scale strength right back at it and laugh. Silent uses Catalyst poisons to ignore the strength race.
What is a common mistake? I’d say trying to outlast it. The fight is designed to punish slow decks. end it quickly or it snowballs.
Kin Priest
I call the Kin priest a classic Act 1 gatekeeper. It summons small kin adds that heal the main body. Then it swings with multi hit holy blasts. It is a bit annoying but still defeatable.
How to Beat Kin Priest:
Many people ask what’s the best way to beat Kin Priest, I say there are 2 main ways for that:
- Safer path (I recommend it for most runs): Prioritize killing the two Kin Followers first. They have lower HP, and deal heavy melee. Clean them to reduce incoming damage fast and stop strength stacking. Use AoE cards (if available), multi-hits, or cheap attacks to burst them down. Once gone, block the Priest’s debuffs and race it down.
- Aggressive path: Rush the Kin Priest directly. Killing it causes the Followers to flee instantly, ending the fight quicker. Ideal if you have 40 to 60 damage front loaded. Risky if Followers ramp up.
Vantom
Among the Slay the Spire 2 bosses, Vantom is that slippery serpent boss that grows a massive tail for huge single hits. It applies something called Slippery, a debuff that makes your attacks deal almost no damage for several turns. The fight ramps fast once the tail comes online, so you cannot afford a slow start.
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How to Beat Vantom
Remove Slippery immediately with any cleanse or relic proc. Block the tail slam on turn 3 like your life depends on it (Trust me, most deaths happen here).
Burst hard on turn 4 while the tail is still recovering. Lucky Tonic or any card that skips enemy attacks buys you a free turn. Ironclad and Silent both handle this fight cleanly. Necro players need to rush draw to find their exhaust answers and I’m not among them.
My golden rule? Never let the tail grow twice. End the fight before turn 6 and you walk away healthy.
Act 1b: Underdocks
The Underdocks offer a soggy detour from the Overgrowth. It is filled with slimy tunnels and waterlogged foes that demand solid defense against bursty attacks. These Slay the Spire 2 bosses feel more approachable overall, but they still punish bloated decks or poor energy management. Prioritize relics like Kunai or Shuriken here for consistent damage.
Lagavulin Matriarch
This hulking mother Lagavulin starts asleep, much like her STS1 counterpart. She wakes up swinging with heavy melee rams and possibly summons smaller Lags (I hate them) for added pressure. This is an easy one too.
How to Beat Lagavulin Matriarch?
Wake her up on your terms by chipping HP just enough. Then explode with burst on her active turns. Poison decks shred her passively while you block the big hits. Fire potions stun her, actually buy breathing room for you. If you’re Necro, rush draw and exhaust synergy to clear summons fast.
Soul Fysh
Soul Fysh lurks in the depths. It is a spectral Slay the Spire 2 boss that exhausts your hand and forces tough discards with its Beckon mechanic, pulling cards away or limiting plays.
It ramps aggression over time, hitting with ethereal blasts and debuffs that clog your draw. You want my advice here? Card management is the crux. Overextend, and you’ll stall out.
How to Beat Soul Fish?
React to Beckon by playing cheap blocks first and preserving your big guns is a wise strategy. Defect’s orbs shine here, channel through the exhaust. Silent poisons ignore the disruption entirely. Aim for 50% HP by turn 4 to skip the worst phase. Relics like Dreamcatcher help cycle disrupted hands.
Sts 2, Act 2: Hive
Act 2 plunges you into the buzzing Hive, a nightmare of insects and sticky webs that slow your deck and amp up the elites. Slay the Spire 2 bosses here demand real scaling.
If you ask me, I’d say that your deck should hum with powers. Relics like Snecko Eye or Runic Dome shine against heavy fights. Expect 10 to 12 turn grinds if you stall, so layer damage early.
Kaiser Crab
Kaiser Crab clamps down hard, layering absurd block while pummeling with claw barrages that shred unblocked decks. Players rage it’s the toughest Act 2 boss. And yeah, it feels like an Act 3 import with its ramping defenses and chip damage.
You know, it actually mirroring STS1’s Hexaghost vibes. unblockable? No, just tanks hits until you crack the shell.
How to Beat This Kaiser Crab?
Poke with multi hits or AoE to bypass block. Silent poisons melt it passively. Ironclad spots ramp strength to match. Burst the shell when block drops (every 3 or 4 turns). Defect orbs evade the clamps.
Knowledge Demon
Knowledge Demon toys with your deck. It forces choices between stacking debuffs like constant DoT, draw cuts, card limits or energy nerfs. It heals and blasts while you choose and this is rude and I hate it. Prolong it, and penalties bury you.
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How to Beat knowledge demon?
Pick Disintegration first (block the DoT). In turn 3 Stack 30+ block for Barrage. Poison/Thorns ignore choices. Avoid Sloth unless big hitters.
Sap only if bursting soon. Heavy decks laugh at Mind Rot. Silent stacks poison effortlessly so it’s a good choice then. Ironclad flames through. Your deck is too slow? It’s bad. Reroll it for more aggression.
The Insatiable
This Slay the Spire 2 boss is another one which I hate. The Insatiable is a gaping worm that drags you into its maw via Sandpit stacks. Your stack reach zero, you lose a turn and get eaten (That’s why I hate it)
You better draw Frantic Escape cards (play to add stacks back?). Anyway, it ramps Strength (that blue arrow) for massive bites. Huge HP pool screams burst or bust which can drag turn into a suicide.
How to Beat the Insatiable?
Play Escapes surgically. I mean don’t flood hand, but never let stacks hit 0. Buff your Str (Inflame, Setup) for Stomps and Pyre nukes. Primal Force turns deck into rocks if desperate. End in 6 to 8 turns is possible. Choose your Attack Potion wisely, pick rare and effective cards, Tank relic choice and Path to Act 3 feels earned then.
Slay the Spire 2 Act 3 Bosses: Glory
Slay the Spire Act 3 bosses catapult you into Glory (such an irony). Glory is a gilded arena of trials where the elites feel like mini bosses and the real bosses expose every flaw in your build. This is endgame territory (at least in the early access version).
Your deck must click with powers, draw and burst, or you’ll stall out hard. Also Pathing matters in Act 3. Hunt relics and energy upgrades, skip weak cards ruthlessly.
This is a hard phase and that’s Ok if you finish a boss even in the turns 12 to 15.
Doormaker slay the spire 2
Doormaker haunts a labyrinth of shifting portals. It spawns door minions that block your path, buff themselves or unleash surprise attacks.
With low early damage, It feels underwhelming at first, but ramps into a chaotic blender once multiple doors stack. Players call it deceptive, me either and it is TRULY deceptive!
How to Beat The doormaker?
Prioritize door clears with AoE or multi attacks. Silent’s Flying Knee or Defect’s lightning orbs wipe them effortlessly. Block the barrages and stack artifacts to pierce buffs. Burst the main body when doors reset (every 4 turns). Ironclad walls it out with spot weakens. Don’t get greedy during the slam turn, it ends early. Watch timestamped fights for portal RNG. Defeating this annoying boss is worth it.
Test Subject #C10
Test Subject #C10 is the lab freakshow. It has different phases involving buffs, intangibles and adaptive mutations that counter your deck type. It starts fragile but evolves and that’s our problem.
Slow decks die here so if yours is slow, reroll for aggression. Also note that Runic Dome nullifies mutations. You can expect to Finish this #C10 in 10-12 turns; victory unlocks Ascension and I spoke about Ascension in Slay the Spire 2 guide.
General Tips and Strategies for Bosses
Slay the Spire 2 bosses reward tight play more than anything else. Thin your deck every chance you get.
Energy relics and extra card draw turn every fight easier. Block the spikes first, then unload damage. Poison works wonders against high HP tanks like Kaiser Crab or The Insatiable. Strength ramps crush everything else.
Pick your character and lean into its strengths. Ironclad wants to match the boss strength and exhaust big hits. Silent stacks poison and clears adds without mercy. Defect channels orbs through disruptions. Necro and Regent need fast draw to hit their combos before they get overwhelmed.
Path smart. Grab block potions and burst relics early. Skip shops that offer nothing for your build. In Ascension runs, reroll seeds if the first boss looks bad for your deck.
The biggest mistake players make is greed. One extra card draw often costs the run. Stay aggressive, block the heavy turns, end fights before they snowball. Most wins happen in 8-12 turns when you follow this.
FAQ
How many bosses are in Slay the Spire 2?
There are 10 main bosses in the current Early Access version, spread across three Acts.
Is there an Act 4 in Slay the Spire 2?
No. Act 4 is not in the game yet, but developers plan to add a proper ending in the full release.
What is the hardest boss in Slay the Spire 2?
Most players struggle with Kaiser Crab and The Insatiable because they scale quickly and punish slow decks.
What is the easiest Act 1 boss?
Kin Priest and Lagavulin Matriarch are usually the easiest if you clear their adds quickly.
How do you beat Doormaker?
Focus on destroying door minions first, block big attacks, then burst the main boss when the doors reset.
How long do boss fights usually last?
Most boss fights take 8–12 turns if your deck has good scaling.
What is the best strategy for boss fights?
Use scaling damage, keep your deck small, block heavy attacks before going all in.
Can I kill the Priest first to end it instantly?
Yes, if you burst it down, Followers flee. But most players prefer clear minions unless you’re confident.
