Mega Crit shipped the second major main branch update to Slay the Spire 2 on June 19 2026, and it changes three things at once. The Act 3 boss called the Doormaker is gone, replaced by a new boss named Aeonglass. The random number system that a player proved was exploitable has been torn out and rebuilt. And official Steam Workshop support is live for everyone. The studio rolled four sets of beta patch notes into one release, so players who were not following the test branch are getting months of changes in a single download.
What changed about the Act 3 boss?
The Doormaker was removed because Mega Crit decided it sat over the complexity threshold the team wanted for an Act 3 fight. Cofounder Casey Yano framed the decision as starting fresh rather than continuing to patch a boss that had lingering problems. In its place stands Aeonglass, a fight built around pressure and consistency rather than puzzle solving.
Aeonglass plays like a damage race. It pumps Wither cards into your hand, and those cards deal damage to you if they are still sitting there at the end of your turn. The threat ramps as the fight goes on, because the boss can upgrade those curses to hit harder. That forces players to rethink late game pathing and which relics they prioritize on the climb toward the final act. Enemy reworks elsewhere, including a tougher Infested Prism, push the same direction. The game is meant to feel harder but fairer.
Why did Mega Crit rip out the random number generator?
The old system let players predict outcomes they should not have been able to see. Slay the Spire 2 used a pseudo random number generator fed by seed values, and because of how the studio seeded different parts of a run, the results ended up correlated. A player who went by the handle Tckmn spent roughly eight hours testing the behavior and proved the correlation was real, which let knowledgeable players forecast unrelated events inside a run.
Mega Crit replaced the underlying algorithm with xoshiro256 to break those correlations. The studio thanked Tckmn directly in the patch notes and warned, in its own words, that suffering is now truly random. The fix matters because once an exploit like that is known, the player base tends to lean into unfun pattern memorization, which quietly drains the tension that makes a roguelike work.
What does Steam Workshop support unlock?
Full Steam Workshop integration means players can browse and install community mods directly through Steam instead of managing files by hand. That single change tends to produce an explosion of custom characters, relics, and challenge runs, because it removes nearly all of the friction from sharing and updating mods. The update also brought the in game Bestiary out of the beta branch, giving players a reference for enemy behavior as they learn the new fights. Slay the Spire 2 is still in early access, and updates like this one are how Mega Crit is steering the full release. If you want to climb the new Spire, the game is on Steam.