Slay the Spire 2 Major Update Fixes Broken RNG, Adds Steam Workshop and New Act 3 Boss

Mega Crit has shipped Major Update 2 for Slay the Spire 2, version 0.107.1, arriving June 19, 2026. The patch overhauls the game's random number generation, introduces Steam Workshop mod support, adds a monster Bestiary, and replaces a long-standing Act 3 boss — changes that cap off a months-long community conversation sparked by one player's exhaustive eight-hour investigation into the game's randomness.

The RNG Problem — and the Player Who Proved It

The headline fix addresses a flaw in Slay the Spire 2's pseudo-random number generator that had been quietly undermining the game's core promise of unpredictability. A player known as Tckmn spent eight hours documenting the irregularities in video form, eventually demonstrating that separate randomness systems inside the game were leaking information to each other. The most illustrative example: a player could predict curse outcomes from Neow's Bones based solely on which floor they chose in Act 1 — two systems that should have no bearing on each other. Mega Crit acknowledged the findings directly, stating the investigation proved "we did, in fact, have some unusual RNG problems." The studio credited the player's work as instrumental in identifying the issue. The fix replaces the old PRNG with xoshiro256**, a modern algorithm. According to Mega Crit, the correlation between Act 1 random rolls and Neow's Bones random rolls now shows no detectable pattern, meaning card rewards, relic drops, and enemy encounters should finally behave as genuinely independent systems.

Steam Workshop and the Bestiary

Beyond the RNG correction, v0.107.1 brings official Steam Workshop integration — the update's most broadly accessible new feature for players who weren't already deep in the modding scene. Workshop support lets players browse and install mods directly through Steam with automatic synchronization across devices, lowering the barrier for community-created content. Also new to the main branch is the Bestiary, a compendium section that logs every monster players have encountered, displaying movesets and animations for each entry. Mega Crit says statistics and lore will be added to the Bestiary in future updates.

Aeonglass In, Doormaker Out

The update also makes a significant structural change to Act 3. The Doormaker, previously the act's boss encounter, has been removed from the game. Its replacement is Aeonglass, a new boss that Mega Crit designed to sidestep the balance and complexity problems that plagued the Doormaker. The change reshapes the late-game experience for every run. Enemy rebalancing extends beyond the boss slot. The Infested Prism elite was completely redesigned. Multiple Axebot variants were consolidated into a single, harder encounter. The Skulking Colony received HP and ability adjustments, and a range of other enemies saw HP tweaks scaled across Ascension difficulty levels. Major Update 2 marks a meaningful inflection point for Slay the Spire 2's early access period. The RNG overhaul in particular addresses something foundational: players can now trust that the game's randomness is actually random. Combined with mod infrastructure and a new boss, the patch moves the game noticeably closer to a feature-complete state — and demonstrates that detailed community research can carry real weight with Mega Crit.