I know this idea is highly unlikely to be even considered, but here's my pipe-dream:
A skill called "Arson", which gives you the ability to set ablaze your enemies crops, buildings, villages; in short: add fire to the game (besides a camp fire, that is). Will require a "Potions and Herbs" recipe to make "Accelerant". Then you spread the accelerant, start a normal fire on one of the accelerant tiles, and watch as it spreads and destroys!
Ah, like I said, I'm just dreamin'...