Slay the Spire 2 · Boss guides
How to beat every Slay the Spire 2 boss
Slay the Spire 2 Early Access ships three acts. Act 1 rolls one of two biomes per run — Overgrowth or Underdocks — each with its own boss pool; Act 2 (The Hive) and Act 3 (Glory) each offer three boss options. There is no Act 4 / Heart fight yet. Every confirmed boss below has its own how-to-beat page.
Act 1
Act 1 bosses — Overgrowth & Underdocks
Act 1 uses alternate biomes: a run rolls either the Overgrowth or the Underdocks layout, and you face one boss from that biome's pool of three.
Overgrowth
How to beat Ceremonial Beast
A dormant brute that spends its opening turns powering up — stacking Strength and a Ritual-style per-turn buff — before waking into escalating multi-hit attacks. The longer the fight runs, the harder every hit lands, so it is fundamentally a race against its own scaling.
How to beat The Kin
A multi-enemy fight: a back-line Kin Priest that piles on Frail and Weak while front-line followers deal the bulk of the melee damage and buff their own Strength. It is a target-priority puzzle, not a damage check.
How to beat Vantom
An ink-themed predator that alternates between an aggressive stance (heavy single hits plus Frail to choke your block) and a defensive stance where it stacks block and charges a large delayed swing. Reading which stance it is in dictates whether you defend or commit.
Underdocks
How to beat Lagavulin Matriarch
Starts asleep behind heavy armor and, once awake, repeatedly debuffs your Strength and Dexterity while buffing her own. Every drain cycle permanently weakens your attacks and block, so the fight only gets worse the longer it lasts.
How to beat Soul Fysh
A pattern fight: Soul Fysh dumps Beckon status cards into your deck (1 energy; if not exhausted or discarded by end of turn they hit you for unblockable damage) and periodically turns Intangible, reducing your hits to 1. Winning means cycling Beckons out and saving burst for the windows it is vulnerable.
How to beat Waterfall Giant
A large solo body whose signature trick is that it does not die at 0 HP — instead it detonates on its next turn, so the lethal blow is followed by a big explosive blast you have to survive.
Act 2
Act 2 bosses — The Hive
Three possible bosses, each leaning on a different deck-warping gimmick — a soft kill timer, escalating choice debuffs, and an armor-stacking body.
How to beat The Insatiable
A soft enrage timer: it opens with a Sandpit countdown that kills you in a set number of turns. You extend the timer by playing the Frantic Escape cards it adds to your deck, but each Escape you play costs more the next time — so you are racing to kill it before you run out of escapes.
How to beat Knowledge Demon
A choice-based punisher: each time it would debuff you it instead makes you pick the lesser of two escalating downsides (take end-of-turn damage, draw fewer cards, cap your cards per turn, or permanently lose energy). The choices get harsher the longer the fight goes.
How to beat Kaiser Crab
A body flanked by two claws that layers heavy block while battering you with claw barrages. Destroying one claw reportedly makes the other surge with Strength and a wall of block for a turn, and clearing both ends the fight — so block management and bypassing armor are the core problems.
Act 3
Act 3 bosses — Glory
The current Act 3 gauntlet. Note: the old Doormaker boss was removed in patch 0.105.0 and replaced by Aeonglass, so it is not listed here.
How to beat Queen
A two-stage fight. She arrives with a minion (a Torch Head Amalgam) and a Chains of Binding mechanic that 'binds' the first cards you draw each turn so you can only play one of them, on top of heavy long-duration debuffs. The minion must fall before you can properly close on her, and she follows a predictable buff/multi-hit/nuke cycle.
How to beat Test Subject
A multi-phase marathon: it revives into successive phases with more HP and a fresh modifier each time, and cleanses its debuffs on transition. Reported phases punish Skill spam (gaining Strength), insert Wounds on unblocked hits, and go Intangible on alternating turns — so each phase demands a different gameplan.
How to beat Aeonglass
The newest Act 3 gatekeeper, added in patch 0.105.0 to replace the removed Doormaker. Its Withering Presence punishes wide, cheap-card decks: after you play enough non-status cards across the fight, it forces a Wither status card on you (a 1-energy Retain/Exhaust card that damages you if left in hand). It runs a short rotating pattern with a permanent self-buff each cycle, so finishing fast matters.
New to the climb? Start with the beginner guide and the ascension primer.