rolled 2, 1, 3 = 6
Everything is in order. The Bira move forward in a line, with you on the right end, all of them wheeling carts of additional fuel behind them. Not long after you enter the fog, the skittering begins again, and you say as much, though your comrades don't hear anything. As before, the spider swarm appears at the edge of your aura, and is lit like a torch. For several minutes you pour it on, listening to the horrible shrieking as you unload the weapon into the advancing ranks.
In the end, you are forced back before you need to reload, cursing the creature's control over your mind. The Bira continue without you, sending you their thanks for the weapons. Once you're out, you remove the flamethrower and sit down, waiting with the others just behind the trenches. Not long after that, the large beings return, dragging carts still half-full with sloshing fuel.
The leader reports that the spiders have turned back.
The fog begins to dissipate, dragging the edge away from the camps. The commander orders everyone to hold, and within minutes, the fog has pulled back at least three miles, finally stopping about a mile and a half from the center. Not quite a victory, but a serious blow to the hybrids.