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Killing Floor 3 (KF3)

Best Firebug (Devlin) Builds and Skills

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★ Disclaimer: Our guides were written before the Rearmament update, so some information may be outdated. We appreciate your support!
News: Crossplay | Game Pass | Roadmap
Best Settings | Teams | Weapons
Best Bonus Abilities | XP Farm | Difficulty

Killing Floor 3 Devlin Specialist and Character Info

The Firebug Perk, played by Devlin, is the Specialist in Killing Floor 3 (KF3) who can burn down hordes of ZEDs with ease. See the Firebug's best builds, weapons, bonus ability priority, tools, skills, how to play them, and additional character info here!

Best Firebug (Devlin) Builds

Best Firebug Loadout

DevlinFirebug Primary
Sidearm
Tool
Passive Throwable Gadget
Killing Floor 3 Unknown Skill Icon Too Hot to Handle
Lvl 2
Killing Floor 3 Unknown Skill Icon Boom Out
Lvl 4
Killing Floor 3 Unknown Skill Icon Ready for Action
Lvl 6
Killing Floor 3 Unknown Skill Icon Focus Fire
Lvl 8
Killing Floor 3 Unknown Skill Icon Capacity Increase
Lvl 10
Killing Floor 3 Unknown Skill Icon Footlights
Lvl 12
Killing Floor 3 Unknown Skill Icon Fuel to Burn
Lvl 14
Killing Floor 3 Unknown Skill Icon Out With a Bang
Lvl 16
Killing Floor 3 Unknown Skill Icon Red Carpet
Lvl 18
Killing Floor 3 Unknown Skill Icon Hotfoot
Lvl 20
Killing Floor 3 Unknown Skill Icon Capacity Increase
Lvl 22
Killing Floor 3 Unknown Skill Icon Hot Streak
Lvl 24
Killing Floor 3 Unknown Skill Icon Extinguisher
Lvl 26
Killing Floor 3 Unknown Skill Icon Hot Mess
Lvl 28
Killing Floor 3 Unknown Skill Icon From the Ashes
Lvl 30
Tier List Evaluations
Solo
S tier splat▶︎ Best at Solo Missions
Squad
B tier Splat▶︎ Fires causes team problems

✘ Click on an equipment category to jump to their selection explanation.

Purchase the Dragon's Breath shotgun early for a reliable weapon that handles medium to lower-tier ZEDs with ease. Use it with your starting gear until you can afford the Vulcan TA, your main damage dealer capable of bursting down any ZED in its single-fire mode.

The Pyre .357 pistol is also highly effective, even at medium to long range. Early on, it excels at taking out Husks by one-shotting their gas tanks, headshotting fire-resistant Bloats, and it boasts the highest Ballistic damage among all sidearms.

Since the Firebug burns through ammo quickly, the Ammo Bag is a great investment to keep your supplies up at a low Dosh cost.

Best Classes Tier List

Firebug Best Weapons

Jump to a Weapon Slot!
Primary Secondary

Best Firebug Primary Weapons

Primary Weapon Slot 1

Primary
Recommended Mods

The Vulcan TA is one of the strongest weapons in the game. Its Primary single-fire mode can burst down hordes of small and medium ZEDs with high direct hit damage with solid AoE. You can also charge shots to eliminate Husks, Bloats, and Sirens from a distance, and even help bring down large ZEDs when needed.

We recommend prioritizing the Mods listed above that enhance the Primary firing mode. These mods improve single-fire accuracy, reduce ammo consumption, and further boost its overall DPS.

Primary Weapon Slot 2

Primary
Recommended Mods

The Dragon's Breath shotgun is a strong early-game weapon for Waves 2–3, handling most ZEDs with ease before Scrakes and Fleshpounds appear. It offers great crowd control while having respectable range for a shotgun.

Use Mods that boost damage, accuracy, and handling with minimal drawbacks, and equip a Drum Mag for more sustained fire in the preferred Secondary burst firing mode.

Alternative Primary Weapons

1 Killing Floor 3 IfritIfrit Primary DMG: 110
Primary Fire Mode: Heat DMG
Secondary DMG: 400
Secondary Fire Mode: Electrical DMG
Base Cost: 4,500
2 Killing Floor 3 Incinerator M7Incinerator M7 Primary DMG: 60
Primary Fire Mode: Heat DMG
Base Cost: 3,500
3 Killing Floor 3 IR-50 BrimstoneIR-50 Brimstone Primary DMG: 100
Primary Fire Mode: Heat DMG
Base Cost: 1,400

The Ifrit Engineer weapon is a decent alternative for Firebugs. Its primary fire deals Heat damage and functions like an auto-shotgun, making it effective at close range.

If you prefer a more classic, flamethrower spraying playstyle over direct-hit weapons, consider using the Incinerator M7 or the Vulcan TA's secondary fire mode, focusing on AoE and skills that boost ground fires.

Best Firebug Sidearm Weapon

Sidearm
Recommended Mods

The Pyre .357 has the highest base Ballistic damage among sidearms and is perfect for taking out ranged ZEDs like Husks, Sirens, and Bloats early on. These mid-tier ZEDs are more resistant to Heat damage, so a few well-placed shots to their weak spots with the revolver will take them down quickly.

Alternative Sidearm Weapons

1 Killing Floor 3 KH-380KH-380 Primary DMG: 60
Primary Fire Mode: Ballistic DMG
Secondary Fire Mode: Biological DMG
Base Cost: 800
2 Killing Floor 3 KraitKrait Primary DMG: 55
Primary Fire Mode: Ballistic DMG
Base Cost: 900

The KH-380 is a good substitute if your team lacks a Medic and needs extra healing support. If you prefer spraying over precision, the Krait automatic pistol is great for dealing with ZEDs up close, though it lacks the stopping power, accuracy, and range of the Pyre .357 for picking off Husks and Bloats.

Firebug Best Tools

Best Firebug Tools

Tool Effect
Killing Floor 3 Ammo BagAmmo Bag Supply drop that allows the team to refill their ammunication midbattle.
• 1 deployable bag
• Each bag grants ammo for current weapons and 1 grenade

The Firebug burns through ammo quickly due to dealing with large groups of small and medium ZEDs, along with high ammo consumption weapons. Carrying extra Ammo Bags helps keep you stocked at a low cost.

Alternative Tool

Tool Effect
1 Killing Floor 3 Multi-ToolMulti-Tool Multi-function tool with 3 charges.
• Activates and allows remote enabling of Traps.
• Enables Ziplines
• Unlocks Armor Lockers and certain Doors
• Repairs damaged Explosive Locks
2 Killing Floor 3 Pulse LurePulse Lure Ultrasonic device which acts as a distracting lure for enemies, drawing them to its location.
• 3 lures
Nearby enemies are Confused, causing them to attack other nearby enemies

The Multi-Tool is a versatile pick for any class and provides strong team support. It lets you access Ziplines and Armor Containers for mobility and defense. You can also use it to unlock special doors and access Turrets, giving you flexible options for strategizing and surviving waves.

The Pulse Lure is another strong option, helping you group up large numbers of ZEDs for easier crowd control and maximizing your AoE damage.

Firebug Bonus Ability Priority

Ability and Priority Explanation
Teammates with the lowest Health within 10m gains 1 Health after killing an enemy.
★★★★★
The Firebug itself is not lacking in the damage department, but she has the clear weakness when it comes to support. With this bonus ability, you can use the Firebug's already solid clear to burst heal the ally with the lowest health.
Add 10 Panic Power.
★★★☆☆
The additional Panic power will increase the likelihood of your flames to cause ZEDs to panic, allowing you and your team more space!
Damage from Bosses is reduced by 5%.
☆☆☆☆
The Firebug, while having self-healing, can be quickly dealt with by Bosses as their mobility can get the best of them. This ability allows you to make a few more mistakes before biting the dust!

For the Firebug, it would be best to prioritize the following Bonus Abilities to allow its already high damage and clear to further support allies by providing auxiliary heals and generating crowd control with Panic.

List of Bonus Abilities for Mods

Best Firebug Skills

Jump to a Skill Type!
Passive Throwable Gadget

Best Devlin Passive Skills

Skill
Level 2
Killing Floor 3 Unknown Skill Icon Too Hot to Handle

Base Effect: Retaliate with a small burst of flame that applies Burn and 150 Heat damage against enemy melee attacks.
┗ This skill has a 16 second cooldown between triggers.
┗Burn afflicts enemies with heat damage over time.
Level 8
Killing Floor 3 Unknown Skill Icon Focus Fire

Base Effect: Deal 10% increased direct weapon damage with Heat weapons.
Level 14
Killing Floor 3 Unknown Skill Icon Fuel to Burn

Base Effect: Max ammo capacity is increased by 30%.
Level 20
Killing Floor 3 Unknown Skill Icon Hotfoot

Base Effect: Ground fire effects caused by weapons heal you for 2 health per second while standing in them.
Level 26
Killing Floor 3 Unknown Skill Icon Extinguisher

Base Effect: Weapon reload speed is increased by 10%.
┗ Reloading weapon damages nearby enemies applying Panic and 75 heat damage. Burning enemies take triple damage, but are extinguished.
┗Burn afflicts enemies with Heat damage over time.
・Panic interrupts enemies, causing them to helplessly writhe in place

This build focuses on making the Firebug a powerhouse with direct hits and explosive AoE. With weapons like the Vulcan TA and Dragon's Breath, Focus Fire boosts direct hit damage to melt through hordes more efficiently.

Too Hot to Handle provides a defensive buffer for enemies that get too close, while Fuel to Burn increases ammo capacity, which is crucial for a class that consumes a lot of it.

Though this setup doesn't rely heavily on ground fire mechanic for damage, Hotfoot makes it incredibly useful for healing when needed. Finish with Extinguisher for a reload speed boost that increases DPS and damages nearby enemies even while reloading.

▲ Jump to the Top ▲

Best Devlin Throwable Skills

Skill
Level 4
Killing Floor 3 Unknown Skill Icon Boom Out

Base Effect: Increased Molotov explosion radius by 25%.
Level 10
Killing Floor 3 Unknown Skill Icon Capacity Increase

Base Effect: Throwable carrying capacity is increased by 1.
Level 16
Killing Floor 3 Unknown Skill Icon Out With a Bang

Base Effect: Molotov explosion damage is increased by 100%.
Level 22
Killing Floor 3 Unknown Skill Icon Capacity Increase

Base Effect: Throwable carrying capacity is increased by 1.
Level 28
Killing Floor 3 Unknown Skill Icon Hot Mess

Base Effect: Molotov secondary projectiles explode and when they land, dealing 150 Heat damage in additional to spawning ground fire.

This skill setup emphasizes the explosive power of the Molotovs, boosting direct explosion damage and blast radius over lingering fire effects. Hot Mess also adds some ground fire coverage, which pairs well with Hotfoot for emergency healing.

▲ Jump to the Top ▲

Best Devlin Gadget Skills

Skill
Level 6
Killing Floor 3 Unknown Skill Icon Ready for Action

Base Effect: Using Wildfire reloads weapon and increases weapon damage by 10% for 10 seconds.
Level 12
Killing Floor 3 Unknown Skill Icon Footlights

Base Effect: Ground fires created by Wildfire have 25% increased radius and deal 15% increased damage.
Level 18
Killing Floor 3 Unknown Skill Icon Red Carpet

Base Effect: Ground fire created by Wildfire last for an additional 3 seconds.
┗ Standing in ground fire created by Wildfire grants 20% increased heat weapon damage.
Level 24
Killing Floor 3 Unknown Skill Icon Hot Streak

Base Effect: Killing nearby enemies grants 3 gadget activation energy.
┗ Gadget kills do not count towards this.
Level 30
Killing Floor 3 Unknown Skill Icon From the Ashes

Base Effect: Once per match, while downed you may activate Wildfire to get back up, repair 20 Armor intergrity, and become invulnerable for 4 seconds.

These skills make Wildfire more than just a powerful AoE blast and grant you powerful buffs. Ready for Action increases your damage post-activation, while Footlights boosts it further when standing in the ground fire it creates.

Red Carpet extends the duration of ground fire and further increases your damage while standing in it. Take Hot Streak to build Wildfire energy faster with each kill, and From the Ashes as a valuable self-revival tool, especially useful on higher difficulties.

▲ Jump to the Top ▲

Firebug Skill Priority

Devlin Skill Upgrade Priority

Skill Priority Explanation
Killing Floor 3 Unknown Skill Icon Focus Fire ★★★★★ Focus Fire is the top priority, as this build emphasizes direct hits over lingering burn damage. It directly boosts the impact of your primary weapons, the Vulcan TA and Dragon's Breath.
Killing Floor 3 Unknown Skill Icon Too Hot to Handle ★★★★ Too Hot to Handle allows for a good riposte mechanism, allowing you to harm enemies that get too close, and grant a possible window for repositioning.
Killing Floor 3 Unknown Skill Icon Hotfoot ★★★☆☆ For extra healing, Hotfoot is an easy way to boost your survivability simply by standing in the ground flames you create. Upgrade this to boost the heals greatly.
Killing Floor 3 Unknown Skill Icon Red Carpet ★★☆☆☆ Red Carpet is good to level simultaneously as Footlights, for upgrading the former increases the duration of Wildfire's ground flames.
Killing Floor 3 Unknown Skill Icon Footlights ★★☆☆☆ Upgrading Footlights increases your overall damage when standing in the Wildfire ground flames, pairing perfectly with Red Carpet.

Focus Fire is the priority in this build, maximizing the powerful direct-hit Heat damage of your main weapons, the Vulcan TA and Dragon's Breath.

For added survivability, upgrading Too Hot to Handle lowers the cooldown of its defensive utility, while upgrading Hotfoot increases the passive healing received when standing in ground fire.

To top it off, upgrade Red Carpet and Footlights together to further boost your damage and increase the duration of ground fires after using the Wildfire gadget.

How to Play Firebug

Firebug Playstyle Tips


Prioritize Direct Hits

We recommend focusing on direct hits over AoE burn effects, as they deal significantly more damage overall. This is especially effective in boss fights, where you're targeting a single, fast-moving enemy. Direct hits provide much higher burst damage in these situations.

Line Up ZED Crowds to Burst With AoE

To conserve ammo and maximize damage, aim to line up multiple ZEDs with each shot rather than targeting them one by one. Clusters can be wiped out efficiently with the Vulcan TA’s explosive shots and Dragon's Breath shotgun blasts.

Don't Rush to Set Large ZEDs on Fire

When a Scrake or Fleshpound is lurking, be careful not to accidentally set them on fire and trigger their rage before your team is ready to take them down. Burning them too early can make the fight much harder.

All Devlin Skills

Firebug Passives

Level 2
Killing Floor 3 Unknown Skill Icon Firewall
Killing Floor 3 Unknown Skill Icon Too Hot to Handle
Level 8
Killing Floor 3 Unknown Skill Icon Heat Exposure
Killing Floor 3 Unknown Skill Icon Focus Fire
Killing Floor 3 Unknown Skill Icon Scorched Earth
Level 14
Killing Floor 3 Unknown Skill Icon Fuel to Burn
Killing Floor 3 Unknown Skill Icon Slow Cook
Level 20
Killing Floor 3 Unknown Skill Icon Red Zone
Killing Floor 3 Unknown Skill Icon Hotfoot
Level 26
Killing Floor 3 Unknown Skill Icon Extinguisher
Killing Floor 3 Unknown Skill Icon Barbecue Bash
Killing Floor 3 Unknown Skill Icon Explosive Reaction

List of All Passive Skills

Firebug Throwables

Level 4
Killing Floor 3 Unknown Skill Icon Cocktail Party
Killing Floor 3 Unknown Skill Icon Boom Out
Killing Floor 3 Unknown Skill Icon Firecracker
Level 10
Killing Floor 3 Unknown Skill Icon Capacity Increase
Level 16
Killing Floor 3 Unknown Skill Icon Extended Edition
Killing Floor 3 Unknown Skill Icon Out With a Bang
Level 22
Killing Floor 3 Unknown Skill Icon Capacity Increase
Level 28
Killing Floor 3 Unknown Skill Icon Asphyxiate
Killing Floor 3 Unknown Skill Icon Hot Mess
Killing Floor 3 Unknown Skill Icon Up in Flames

List of All Throwable Skills

Firebug Gadgets

Level 6
Killing Floor 3 Unknown Skill Icon Front Row Seats
Killing Floor 3 Unknown Skill Icon Ready for Action
Killing Floor 3 Unknown Skill Icon Heat Therapy
Level 12
Killing Floor 3 Unknown Skill Icon Footlights
Killing Floor 3 Unknown Skill Icon Speedy Exit
Level 18
Killing Floor 3 Unknown Skill Icon Triple Play
Killing Floor 3 Unknown Skill Icon Red Carpet
Killing Floor 3 Unknown Skill Icon In the Public Eye
Level 24
Killing Floor 3 Unknown Skill Icon Hot Streak
Killing Floor 3 Unknown Skill Icon Blast Zone
Level 30
Killing Floor 3 Unknown Skill Icon Double Feature
Killing Floor 3 Unknown Skill Icon Flammable Material
Killing Floor 3 Unknown Skill Icon From the Ashes

List of All Gadget Skills

Devlin Specialist Stats and Information

Firebug Stats Overview

Firebug Stats
Damage
4
Survivability
4
Support
4

Devlin is a Firebug Specialist with an overall score of 4 Damage, 4 Survivability, and 4 Support. They will also start with 2,953 loaded into their Operation Budget at Level 1, which will gradually increase as their Perk is leveled up.

Starting Gear

Primary Sidearm
Killing Floor 3 IR-50 BrimstoneIR-50 Brimstone Killing Floor 3 Pyre .357Pyre .357

Character Information

Devlin Basic Information
Killing Floor 3 Devlin
Perk Archetype Starting Gadget
Firebug Wildfire

Voice Actors

English VA TBD
French VA TBD
German VA TBD
Spanish VA TBD

Killing Floor 3 Related Guides

Characters Partial

List of All Specialist Characters

All Specialist Characters

All Nightfall Specialists
KF3 Foster Foster
Commando
KF3 DevlinDevlin
Firebug
KF3 ImranImran
Engineer
KF3 LunaLuna
Sharpshooter
KF3 ObiObi
Medic
KF3 NakataNakata
Ninja

Other Character Guides

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