What perk level is recommended for this solo run?

At least Firebug level 20, so the fourth skill tier is available to control both small and bigger Zeds.

What weapons are bought for the boss?

Two or three Microwave Guns placed near the arena plus the standard flamethrower for the small Zeds the bosses summon.

Is the guide still up to date?

The author marked it as not current; use it as a historical build and check against current balance.

KF2 Firebug Solo on Hell on Earth - 4-Wave Guide

A Russian guide for players tired of swinging a shovel as Berserker for solo Hell on Earth achievements. The author rates Firebug as the second-easiest perk for these achievements after Berserker (some put it first). The guide is marked "not current" by the author, so treat the numbers as historical. Compare with Firebug ultimate guide and Hell on Earth Berserker/Firebug pillar kiting.

Map and skills

Pick any map but set the game to 4 waves, as for the Berserker route. You need Firebug level 20 or higher; the fourth skill lets you control both small cinders and bigger "steaks".

Build for the four waves of open-fire cooking:

Build for waves Skill selection for waves 1-4.

Even without the level 25 skill it is simple; if you have it, take the left option.

For the boss fight swap the level 10 and 15 skills so you heat the boss longer and more effectively:

Build for the boss Skill selection for the boss wave.

Weapons and tactics per wave

Wave 1. Your flame tool for this wave is the Caulk 'n' Burn flamethrower (called "Inferno" in the Russian text).

The first-wave flamethrower.

Set the Zeds' legs on fire and watch them dance. Do not hold the fire button: tap it every couple of seconds to avoid wasting fuel, since fire stays on the ground for a few seconds.

After wave 1. You have a bit over 1200 dosh and the 100-dosh starting lighter. Sell it and buy the full Flamethrower plus ammo with the rest.

Buying the flamethrower Purchase after wave 1.

Wave 2. Same approach: napalm on the mutants' legs and burning the ground in front of them. A few Scrakes and Fleshpounds will join, taking about five seconds more than normal Zeds. If one gets too close, the level 20 left-branch skill can push enemies back when their face is lit, so aim at the torso instead of the ground and step back, then return to igniting the ground.

Wave 3. With the money, buy the incendiary shotgun.

The incendiary shotgun.

Spend the rest on ammo/fuel and armor. A Fleshpound may show up and is burned like the Scrakes; the shotgun adds heat, especially on Scrakes, which drop after two or three shots. Normal Zeds are burned by lighting the ground.

Wave 4. Same as wave 3, just more Zeds of each type.

Boss wave. Right after wave 4 change the level 10 and 15 skills to the opposite options so the entire left branch is active. Sell all weapons and spend everything on:

The Microwave Gun.
The standard flamethrower (Caulk 'n' Burn).

The Microwave Gun.

The Microwave Gun heats the bosses (and the King Fleshpound's minions); the flamethrower handles small Zeds summoned by the Patriarch and Hans. One Microwave Gun is not enough, especially for Hans and the Fleshpound with their protective fields, so buy 2-3 and drop them near the fight. Kite bosses around an object (such as ambulances on Burning Paris) and never run in a straight line. After a couple of minutes it is an easy win.

Result The finished run.

Conclusion

The guide does not force these weapons or perks; it just shares one way to clear Hell on Earth maps solo as Firebug.

FAQ

What perk level is recommended for this solo run?: At least Firebug level 20, so the fourth skill tier is available to control both small and bigger Zeds.
What weapons are bought for the boss?: Two or three Microwave Guns placed near the arena plus the standard flamethrower for the small Zeds the bosses summon.
Is the guide still up to date?: The author marked it as not current; use it as a historical build and check against current balance.