you sleeping on the flamethrower? Burn builds are no joke
Once you get to the later stages even with an entire burn built, in the few seconds it takes them to burn you die.
With a proper flame cannon build, nothing in the latter stages gets close to you because literally everything on the screen is on fire; spewing more flame bullets when they die.
Helps if you bring in Hina or get a few points in move speed too, as early game sucks until you get fire levels
