KF2 Firebug Guide: Weapon Ratings, Skills, Rated Loadouts

This is a community Firebug guide, reworked several times through 2023, that rates weapons, explains every skill and gives rated loadout tables with the skill-tree codes to match. The ratings are the author's personal opinion on a 5-point scale. For another take see Firebug guide: weapons, skills, loadouts and the Firebug perk page.

What the Firebug is

The Firebug controls crowds and keeps ZEDs away, kills trash fast and adds damage over time with fire. Its unique mechanic is Fire Panic, which can help or hurt. At level 20 it becomes the ultimate crowd-control perk with better survivability. The perk's bad reputation comes from bad players, not from the perk itself.

Weapons

• Caulk n' Burn: the starting flamer, the cheapest to refill, kills trash quickly and is usable up to about wave 10. Short and mid range.
• Spitfire / flare gun (tier 2): arguably the best and cheapest ranged weapon; deadly against trash, great against Gorefasts and Bloats so you do not have to touch them.
• Trenchgun / Dragon's Breath (tier 2): highest damage when all pellets land, best against groups coming from one direction thanks to penetration; bad spread and low ammo.
• Mac-10 (tier 3): a fire SMG that was strong before its nerf; now lacks ammo and damage against mid-tier ZEDs and is not recommended.
• Flamethrower (tier 3): like Caulk n' Burn but with more ammo per magazine and about double damage; fewer reloads between fights.
• Microwave Gun (tier 4): damage similar to the flamethrower. Its alt fire pushes ZEDs away, knocks down most ZEDs, knocks a Scrake down with two alt fires and kills E.D.A.R. fast, but its ground fire is weak.
• Husk Cannon (tier 4): buffed in summer 2019; strong damage and fire rate, but a full refill costs almost 800 Dosh. Best used uncharged or half charged (about 0.215 s delay before the extra ammo is consumed).
• Molotov: throw it at a choke point and keep it safe from trash while you cover your back; it leaves residual fire and benefits from Ground Fire.
• Helios (tier 5, Firebug exclusive): a plasma microwave ranged weapon with some recoil and spread, great damage and fire rate, can headshot; weighs 8 (9 upgraded).
• HRG Incendiary Rifle: balanced, can be upgraded twice, alt fire shoots incendiary grenades; great crowd control but can run short on ammo on later high-difficulty waves.
• Scorcher: clears hordes and can kill big ZEDs, but ammo is its weakness; its alt fire works like extra long-range Molotovs.
• Thermite Bore (tier 4 DLC): launches thermite grenades that stick to ZEDs and surfaces and detonate after 4 s or on alt fire. An excellent crowd control tool, especially in Zed Time, but use it at choke points because of its small ammo pool.

Skills

• Level 5: Bring the Heat (+35% fire damage) is a must. High Capacity Fuel Tank (+100% tank, not total ammo) is not worth it.
• Level 10: Barbecue (burn lasts 150% longer, good for ranged-only loadouts) or Ground Fire (ground fires deal massively more damage and slow ZEDs; best with flamethrower and Caulk n' Burn). Updates: Mac-10 does not benefit, while Spitfire, trench gun and Molotov do. Ground fire from the Microwave Gun deals only 4 damage to big ZEDs, so shoot them directly.
• Level 15: Napalm (burning ZEDs ignite those they touch, burn lasts 150% longer; good for choke points; since v1076 big ZEDs resist Fire Panic more) or ZED Shrapnel (since v1076, ZEDs killed by fire have a 30% chance to explode, with the explosion damage raised sharply from 10, and stun nearby ZEDs; now a real alternative to Napalm).
• Level 20: Heatwave (ZEDs hit at point blank stumble back; Gorefasts and Fiends resist repeats, so wait about 3 seconds, and big ZEDs have a 7-second cooldown) is the main survivability skill. Firestorm (range) is to be ignored.
• Level 25 (Zed Time): Pyromaniac (near real-time attacks and never run out of ammo) is best in every loadout. Inferno (30% slow and +50% burn damage) is situational.

Skill trees and loadouts

Skill codes use L and R by position, for example LRLLL is Bring the Heat, Ground Fire, Napalm, Heatwave, Pyromaniac. The author does not recommend upgrading flamers, because the cost gives only 2-5 extra damage.

Flamers only (tree LRLLR or LRRLL):

Loadout	Rating
Caulk n' Burn + Flamethrower + medic pistol/SMG	4/5
Caulk n' Burn + Microwave Gun + medic pistol	5/5

Ranged only (tree LLLLL or LLRLL; number in brackets is upgrades):

Loadout	Rating
Spitfire(3) + trench gun(2)	5/5
Spitfire(2) + trench gun(3)	5/5
Spitfire(3) + Mac-10 + medic pistol/SMG	3/5
Spitfire(2) + Husk Cannon + medic pistol	2/5
Helios + Spitfire(+2)	5/5
Helios + trench gun(+1)	3.5/5
Husk Cannon + Spitfires(+2) + medic pistol	4/5
Husk Cannon + trench gun(+2)	3/5
Husk Cannon + Mac-10 + single Spitfire	4.5/5

Mixed (use Ground Fire so the flamer deals its best damage):

Loadout	Rating
Caulk n' Burn + flares(3) + medic pistol	4/5
Caulk n' Burn + trench gun(3) + medic pistol	4/5
Caulk n' Burn + Mac-10(3) + medic pistol/SMG	3/5
Caulk n' Burn + Husk Cannon(1) + medic pistol	3.5/5
Flamethrower + Spitfire(2) + medic pistol	4.5/5
Flamethrower + trench gun(3)	4/5
Flamethrower + Husk Cannon	3/5
Microwave Gun + trench gun	3.5/5
Microwave Gun + Spitfire(2)	4/5
Helios + Caulk n' Burn + medic pistol	4.5/5
Husk Cannon + Caulk n' Burn + medic pistol	4.5/5
Husk Cannon + Flamethrower + medic pistol	4.5/5

Off-perk additions: Freezethrower + Spitfire(3) 4/5, Freezethrower + trench gun(3) 3/5, Winterbite + Caulk n' Burn + Helios 5/5, Freezethrower + Helios 4/5.

Newer ranged setups (tree LLRLL or RLRLL)

• Helios + HRG Incendiary Rifle (+ medic pistol): great damage and sustainability; focus on trash to make ammo last.
• Dual Spitfire(3) + HRG Incendiary Rifle (+ medic pistol): strong in Zed Time, a bit less ammo.
• Mac-10 + HRG Incendiary Rifle + dual Spitfire(1) + medic pistol: the author's pick for killing trash with high ammo reserve and flexibility.
• HRG Incendiary Rifle + Scorcher + dual Spitfire(1) + medic pistol (tree RRRLL): Scorcher alt fire acts like an improved Molotov and everything benefits from Ground Fire.
• Mac-10 + Scorcher(2) + dual Spitfire(1) + medic pistol (RRRLL or LRRLL): mediocre; Scorcher has ammo for only about 7-10 big ZEDs.
• HRG Incendiary Rifle + trench gun + single Spitfire (RRRLL or LRRLL): precision only, not for big ZEDs, excellent in Zed Time.
• Thermite Bore + Caulk n' Burn + Spitfire(2) (LRRLL): crowd control for trash and mid ZEDs, roughly up to a Quarter Pound.
• Thermite Bore + trench gun + Spitfire + medic pistol (LRRLL): high output in Zed Time.
• Thermite Bore + Mac-10 + dual Spitfire(1), or + HRG Incendiary + Spitfire(1) (LRRLL): average damage, avoid big ZEDs.
• Thermite Bore + Helios (LRRLL): can kill big ZEDs but ammo suffers.

Thermite Bore loadouts shine at choke points and with good timing; in open areas ammo is wasted on scattered ZEDs.

Takedown notes

The guide links video examples: Freezethrower with trench gun or flare guns against Fleshpounds and Scrakes, Husk Cannon uncharged and half-charged shots against Fleshpounds and Quarter Pounds, Winterbite with Helios or Husk Cannon, Scorcher+2 against Fleshpounds, Scrakes and Quarter Pounds, and HRG Incendiary+2 against Quarter Pounds. It also credits two techniques, "FP delay" and "HVT body block", the first useful to give a Demolitionist time to hit a Fleshpound with an RPG or M32 or to deal with one solo. The author notes that off-perk Freezethrower use works in public games if the team understands what you are doing.