You retreat several steps as you see a member of the Royal Guard backing around the corner toward you. You're certain he is one of the guards who originally chased you down here. He faces away from you and he bears a blazing torch up as if to deflect a blow. His weapon is clutched, shaking, in his other hand. It drips black ichor along its length.
As he backs toward you, you see what's causing the skittering sounds. You'd first taken them for shadows moving along the skulls in response to the torchlight. As the guard gets closer to you, it becomes obvious they are not shadows.
Spiders, hundreds of them, crawl over the skulls, sizes ranging from no bigger than the end of your thumb, to as large as the skulls beneath them. As you watch, more fall from eye sockets and gaping mouths. They all flow in one direction away from you and the guard, toward a shadowy form blocking the corridor beyond.