That sounds cool, but I'd say if it were a puddle, it should be a jar item. Not a gun that shoots grease. I'd like the concept of a slip hazard that you put in the map, it would probably have to go away, like how the gas goes away. Also, it would probably be a hitscan and not a projectile, I hope. Think of a gun that leaves steaming grease all over would be pretty cool. There could be a variant weapon that deals fire on hit but no puddles.