Mutator System

From BossRush Wiki

What Is It?

At the start of every run, the system draws a handful of mutators from a pool of 28 and applies them immediately for the entire run. How many is fixed, set by mutatorCount in the config — 3 by default (adjustable 1-10); what gets drawn is the random part. Mutators can buff enemies, buff the player, or change environment rules.

Zombie Mode is excluded: it has its own independent in-run buff system and does not use this mechanic.

Applicable Modes

ModeRolls mutators?
Standard BossRush
Infinite Hell
From Scratch (Mode D)
Faction War (Mode E)
Blood Hunt (Mode F)
Fate Echo (Mode G)❌ (the nine-wave counter schedule is fixed)
Black Market Duck Cup (Mode H)❌ (what the odds sheet says is what you get)
Zombie Mode❌ (separate system)

How to See Active Mutators

  • An ACTIVE MUTATORS list appears on the left edge after the run starts and shows the total count
  • Every row is labeled Enemy / Boon / Rule, with category colors for quick scanning
  • Hover a row to open the full descriptions on the right; the row you are reading is highlighted
  • The detail panel scrolls when the list is long, and remains open while moving the pointer from the compact list into the details

Configuration

  • Toggle: enableMutators (default: true)
  • Count: mutatorCount, range 1–10, default 3 per run
  • Adjustable via ModConfig UI or config file

Mutator Pool (28 Total)

⚔ Enemy Buffs (9)

MutatorEffect
Swift StormAll enemies movement speed +30%
Iron FortressAll enemies max HP +50% (existing enemies gain HP immediately)
Bullet RainAll enemies fire rate +25%
GiantsAll enemies size ×1.4, HP +40%
RatswarmAll enemies size ×0.6, speed +45% (smaller and faster)
BloodhoundsAll enemies have infinite aggro range — permanently lock onto you
ViciousAll enemies deal +30% gun and melee damage
Enemy MarksmanAll enemies gun scatter −25% (shots are tighter)
FrenzyAll enemies movement speed and fire rate +20%

★ Player Boons (11)

MutatorEffect
Fleet FootedPlayer walk/run speed +35%
SharpshooterPlayer gun crit rate +30%
Trigger DisciplinePlayer fire rate +25%
Steady AimPlayer gun scatter −30%
Fast HandsPlayer reload speed +40%
Lethal StrikePlayer gun crit damage +50%
Long ShotPlayer gun range +30%
Melee MasterPlayer melee damage +40%
TankPlayer max HP +30%
Field MedicPlayer healing effectiveness +50%
Lucky StarPlayer gun and melee crit rate +20%

☠ Environment Rules (8)

MutatorEffectNote
HemorrhageBleed damage speed ×1.5Blood Hunt (Mode F) only
Festering WoundsAll healing effectiveness −40%
UndyingBosses regenerate 5% HP every 10 seconds
Glass CannonPlayer damage +50%, but armor is zeroedApplies to gun and melee
BlitzPlayer move speed +40%, but max HP −20%Current HP is clamped to the new cap
LifestealKilling an enemy restores 8% max HP
Blood PactDirect player kills restore 16% max HP, but healing −30%Direct player kill credit only
Volatile RemainsEnemies explode on death (3m radius, 40 fire damage)Can injure you — watch spacing

FAQ

Q: Are player boon mutators equally likely?
All 28 entries are in the same pool with equal weight. You might roll both "Giants" and "Glass Cannon" in the same run.

Q: Can I reroll or choose mutators?
No. The draw is random and non-configurable mid-run.

Q: Do mutators carry over between runs?
No. All mutators are cleanly removed on any run-end (clear, death, or manual exit).

Q: Does Volatile Remains chain-explode?
No. Only the kill you land yourself sets off an explosion; kills caused by that explosion do not set off more. There is no infinite chain.