Burning Oil passive

How can I make a passive burning oil ability. If I have to use dummy abilities I don't even know how. Can someone help please?

Burning oil is already a passive ability. It is used for the demolisher, but the demolisher needs to research it first, thats all.

and u need Artillery Weapon (or Attack) Type in order to work.....
in other words, it won't leave the fire on the ground unless it's Weapon Type is Artillery...