Alchemical Blood

You have an alchemical mixture that keeps you running.

Element of Fire Oil. This is a special fluid that was developed by the Alchemists that allows them to run. Weekly you must add more of this fluid to your tank. This also grants the construct resistance to fire.
Alchemist Fire. As the Elemental Oil is used by the body to run the waste is collected in one of 4 containers. This waste is Alchemist Fire in each container there is enough fluid to attack with the liquid. As the liquid touches the air it ignites. You must make a normal attack roll and the range is limited to just 5'. If the target is struck it takes 2d4 damage at the start of each of its turns. A creature can end this damage by using its action to make a DC 10 Dexterity check to extinguish the flames. It takes one day to fill one of the containers. If all containers are full you must expel one of the cartridges once per day.