Burning oil is the cornerstone of yaungol warfare. In the days of their greatest warriors, this weapon was more deadly than magic. This burning substance would scar foes, scorch lands, burn away the cover provided by trees, and could rout even a terrifying mantid assault.
It is also an old tactic of the yaungol to light more campfires each night than people they have. In this way enemy spying in the darkness would assume larger numbers of yaungol existed, while their true positions and numbers remained masked.