Rat Lab Mutation Gun: How to Use the Scientist's Signature Tool

The Mutation Gun is the Scientist's R$299 signature tool. Rush it first in your session loadout, pair it with Mutation Index colour literacy, and see its price, access path, and session-reset behavior — current to mid-September 2026.

Quick answer

The Mutation Gun is the Scientist's signature tool in Rat Lab — an R$299 gamepass classified as a direct mutation gameplay tool. Use it to apply colour-coded mutation statuses to subjects during experiments; it holds the top science-lens tool priority, so it is the tool Scientists rush first in their session loadout order.

Who uses it: mutation-focused Scientists. It is ranked as the “Science identity” tool — the item that defines the role, in contrast to emergency defenses like guns or snipers.
What it changes: from the Lab Rat side, the mutation gun and Index colours change a tagged rat's effective HP and options — a Scientist's tag alters what the subject can do and how durable it is.
How to use it well: pair the gun with Mutation Index colour literacy, keep ammo discipline, and expect counterplay — good rat revenge targets an isolated scientist mid-mutation.

One boundary before you spend Robux or a contested unlock: the gun's concrete firing mechanics — what each colour status does, ammo count, range, cooldown or cast time, and the targeting UI — are not currently documented. Check the gun's in-game description and the Updates feed before relying on a colour effect mid-round.

How the Mutation Gun fits the Scientist experiment loop

Roadmap

1
Spawn and claim a workspace
Know which rooms are still powered or usable after the latest patch.
2
Check the Index UI
Confirm colour meanings before you tag allies or rats incorrectly.
3
Unlock tools in-session
Mutation Gun first if contested; Hazmat if the wing is toxic or unstable.
- Take the Mutation Gun first if it is contested
- Pick up Hazmat if the wing is toxic or unstable
4
Read the breach
If Lab Rats are mid three-stage escape, decide contain vs ignore based on your objective timer.
5
Respect Security lanes
Call positions; do not steal their net kills if you still need a living subject.
6
Extract value before death
A dead scientist with zero Index progress wasted the join.

Loadout order under session resets: decide your goal before spawn (science), rush the S-tier tool for that goal first — the Mutation Gun for Scientists — add one survivability piece (vest, armour, or Hazmat), and only then greed sniper or luxury guns.

Science-lens tier standing and the Mutation Gun tool note

Tips

S / A — Mutation Gun

Your job tool (Scientists, Mutations). The tool note reads: “Science identity. Ammo discipline beats spray.” Pair it with Index colour literacy, and never sell Index colours as promo codes.

A — Hazmat Suit

Take it when wings are unsafe; otherwise it sits at B.

A — Armour

Against bite rushes.

B — Guns / sniper

Emergency defense, not identity.

Letters move with patches

Tier standings are goal-relative and patch-sensitive, not absolute power claims. Patches since the 30 July 2026 launch and the mid-September 2026 Forever / Mutation Codes pass updates can nudge the letters — verify the current standing on the Updates feed before you spend.

Mutation Gun and the Mutation Index workflow

The gun is meant to be used with the Mutation Index, not instead of it. Colour and mutation codes track specimens — they are not promo gift codes you can redeem anywhere. Know both ends of the tool: when a Scientist tags you as a Lab Rat, the gun's colour statuses and Index colours change your effective HP and options, so find out what a colour means the moment it lands on you.

Mechanic flow

1
Open the Index first
Open the Index before long experiment chains so you know your target mutation.
2
Log colour codes privately
Log colour codes in a personal note if you are collecting — they are still not promo codes.
3
Weigh All Mutation Codes (R$2499)
Consider it only if Index completion is your main reason to play; it is expensive compared to Hazmat (R$249) or Mutation Gun (R$299).
4
Re-check Updates
Re-check Updates when Evil Science patches mutation behavior.

Access, price, and session-reset context

Comparison

Comparison
Attribute	Detail
Access path	Paid store gamepass. The store's paid options also include Hazmat Suit (R$249), Armored Guard (R$249), MG (R$299), Sniper (R$399), Stronger Bite (R$75), Stronger Leash (R$99), plus Forever unlocks for tools.
Price	R$299 — the price sheets and the Roblox store listing agree (Mutation Gun Price 299).
Catalog description	“Mutation gameplay tool” — also described as a “direct mutation gameplay tool.”
Intended user	Mutation-focused scientists; it is a scientist-relevant paid option.
Value framing	Comfort, not requirements. Hazmat Suit (R$249) and Mutation Gun (R$299) are the common paid quality-of-life pair — the gun is not a requirement for the For Science or New Specimen badges.
Session behavior	Session tool unlocks reset each join — expect to re-earn access to advanced science gear during the round. The Mutation Gun does not appear in the free unlock timeline marks (5/10/15/22/25/30/60m).
Buying advice	Buy only after you understand the free timer path.

One access detail is currently inconsistent: the Scientist lab flow says to unlock tools in-session — Mutation Gun first if contested — while the price sheets, gamepass catalog, and Roblox store listing only show the gun as an R$299 gamepass and never assign it a minute in the free unlock timeline. Treat the R$299 gamepass as the documented access path, and check the in-game store during a round to see whether an in-session unlock slot currently exists. No free unlock minute and no “Mutation Gun Forever” variant for this gun appear in the current pass listings — verify both in-game before planning a free run, and expect any pass ownership to leave the general session-reset behavior for Scientist tools in place.

Practical discipline and counterplay around the Mutation Gun

Mistakes to avoid

Problem: Spraying the Mutation Gun like a combat weapon
Fix: Ammo discipline beats spray — it is a precision job tool, not a sprayer.

Problem: Standing still while tagging
Fix: Rats bring bite and vest buffers (+50 HP). Use doors, elevation, and Security help.

Problem: Finishing a mutation cast in the spot where you fired
Fix: Relocate after loud gunfire.

Problem: Taking first contact yourself
Fix: Let Security take first contact when they exist; your job is not to out-duel shotguns.

Problem: Fighting through mid-lab pileups
Fix: They are where scientists die most — prioritize survival gear, then Index ticks, then ego plays.

Problem: A rat is clearly finishing stage three
Fix: Decide whether your experiment still needs them alive before committing more tags.

Problem: Casting alone in open labs
Fix: Expect revenge targeting — good rat revenge goes after an isolated scientist mid-mutation.

Mistakes to avoid
Problem	Fix
Spraying the Mutation Gun like a combat weapon	Ammo discipline beats spray — it is a precision job tool, not a sprayer.
Standing still while tagging	Rats bring bite and vest buffers (+50 HP). Use doors, elevation, and Security help.
Finishing a mutation cast in the spot where you fired	Relocate after loud gunfire.
Taking first contact yourself	Let Security take first contact when they exist; your job is not to out-duel shotguns.
Fighting through mid-lab pileups	They are where scientists die most — prioritize survival gear, then Index ticks, then ego plays.
A rat is clearly finishing stage three	Decide whether your experiment still needs them alive before committing more tags.
Casting alone in open labs	Expect revenge targeting — good rat revenge goes after an isolated scientist mid-mutation.

Prices, unlock timers, and tier letters are dated to the mid-September 2026 update wave, and the game updates frequently — re-check the Updates feed before trusting any number here in a buy decision.