The tactical situation
The natural cave is oriented East-West. The dwarves are progressing from the East. They crossed a door some 300 yds earlier where the cave had been walled in. The ceiling of the cave drops to 3 ft in many places, making the progress difficult and forcing a crouching position (-2 attack). On the ground, there is a meandering frozen stream. The stream is covered in rubble and ice, making it rough footing (-2 attack, -1 defense). The echoes are severe, making Per checks -3. There is only a single torch lit, held by Goldo, the vision penalty is -1 per 2 hexes beyond a range of 3 from the torch. Finally, the air is thin and toxic, causing double FP damage.