update · April 10, 2026
Stellaris Open Beta 4.3.4 Cetus Update Adjusts Fleet Caps and Weapon Balance
Stellaris Open Beta 4.3.4 'Cetus' introduces fleet MIA caps, disruptor anti-regeneration effects, and economy production boosts. The update also resolves major out-of-sync issues and refines AI budgeting behaviors.
Paradox has pushed the 4.3.4 'Cetus' update to the stellaris_test branch, bringing widespread balance tuning, bug fixes, and critical stability improvements. The patch targets edge cases in fleet reinforcement sizes, weapon utility, and empire economy management.
Weapon Balance and Fleet Adjustments
Disruptor weapons now apply a regeneration effectiveness penalty on hit for 10 days, scaling from minus 20 percent on Tier 1 up to minus 50 percent on Tier 3. Psionic disruptors apply a minus 35 percent shield regeneration and minus 20 percent fire rate penalty. Fleets are now hard-capped at a maximum of 10 years spent MIA, excluding phased, eaten, or astral rift-exploring fleets. Voidworm fleet power values have also been reduced to better match their capabilities against point defense.
Economy and Building Tweaks
Advanced Bio-Reactors see increased exotic gas production, moving from 0.05 to 0.1. Ministry of Production and Production Center alloy and consumer goods bonuses double from 0.1 to 0.2. Faculty of Archaeostudies biographers on relic worlds now yield more minor artifacts, and the minor artifact storage cap increases to 2,000, or 3,000 with the Archaeo-Engineering AP. Astral Siphon buildings produce increased thread while having their physics bonus and upkeep costs adjusted.
AI and Stability Fixes
The AI budget for alloys, food, and influence has been updated to handle starbase costs, bio-ship fleet rebuilding after lost wars, and vassalization contract changes more effectively. Stability updates resolve multiple out-of-sync (OOS) errors connected to hotjoining players, client disconnections, and spy networks.
Bug Fixes and Rule Adjustments
Mutagenic Habitability restrictions now match their stated thresholds. Calculations for random and naval capacity fleet creation have been corrected to account for larger modern ship sizes, preventing oversized reinforcements during revolts and civil wars while boosting the Doom of the Eater fleet to compensate. Purges across all categories now automatically pause whenever a ground battle takes place on the affected planet.
Why this patch matters
The Cetus open beta addresses long-standing economic imbalances and fleet calculation errors while introducing much-needed utility to disruptor weapons and stabilization fixes for multiplayer sessions.