The Flamethrower has near equivalent power to the m90 shotgun, it lasts longer cuz it has gasoline canisters for ammo, most likely the second best to the flood and you get to see awesome animations of grunts, brutes or any enemy ON FIRE! if u dont believe me , maybe u should check CMT version of Halo 1 PC, its a Halo CE CE= Halo Custom Edition Combat Evolved, and its pretty effective against the flood if u ask me