Can you spread fire in a Yard or Garden type of board or does it have to be on a structure like a Storage Shed or Porch(per Pyromaniac card). The reason i ask is because with only 1 Fire Extiguisher, you can basically set the whole game area on fire and roast all the Investigators...they would not stand a chance(using 4 Investigators). Thx in advance!

I actually came here to post exactly this, having just finished Story 3. By the time the game was over, the Heroes had used their fire extinguisher long ago, and most of the above ground parts of the map were in flames. Is there some other way to deal with the fire, or are the Heroes just doomed to take 2 damage every turn when above ground?

You may use it as variation and put, I dont know, 3 skill points token on fire extinguisher. Removing one every time it used to extinguish the flame and after all skill points on it was used you can just leave it in the game as 2 damage blunt melee weapon.

Also, in the places you extinguished fire you can place another token, which will be considered as place which can't be set on fire again.