Somewhere, a battle rages.
The churning of hundreds of feet has turned the ground from snow to thick, treacherous mud. Flurries of snow limit visibility, but the valley walls shield the battlefield from the worst of the biting wind.
A seemingly-endless tide of shadowy, incorporeal shapes streams into the valley from the north, breaking like a wave against disciplined ranks of soldiers in plate armour. Many of the soldiers wield weapons that glow with pure, white light and seem to be more effective against their insubstantial foes.
Not all their foes lack substance, though. Where the shadows pass, the bodies of the dead rise up, turning their swords against their former comrades. Other, older corpses, their flesh long since fallen from their bones, march alongside the shadows, brandishing rusty spears and battleaxes.
The air is full of shouted orders, cries of pain, clashing steel, and the spine-chilling screeches of the shadows.