Flame battle droids were powered-up versions of the B1 battle droid, used by the Confederacy of Independent Systems. They had upgraded flamethrowers that spat fireballs that could take out goombas, koopas, piranha plants, and mynocks. Jedi proved more resistant to the flame battle droids' weaponry, but some of the younger Padawans went down after getting hit a few times.
The power-up occurred when a B1 ingested a Fire Flower. Like B2 super battle droids, they could withstand one additional blaster hit before dying.