When is the Doctor?
In the darkness, in the shadows, lie the Vashta Nerada. You can see them sometimes, the motes in beams of sunlight, but it is when you cannot see them that you should be the most afraid. They are a swarm of darkness, a killing shadow. They have a hundred names on a million different planets and every name is fear and death. They are the reason that we fear the dark. Vashta Nerada are microscopic organisms that hunt in swarms. Each individual Vashta Nerada seems to absorb light and, when they are swarming in great numbers, it is as if the dark itself is hunting you. However, they are so minute that when they gather in small numbers they are almost invisible. When they hunt, they are looking for one thing: flesh. Unlike most microscopic organisms, they are entirely carnivorous; existing only to consume meat in any form they can find it. In smaller numbers, they exist on road kill and anything else they find that cannot defend itself. In very large numbers, the swarm is so dense that they can turn a human being into nothing more than a bleached skeleton in a matter of seconds.
Luckily, Vashta Nerada are usually found in small numbers. They are an arboreal creature mostly found in forests. Plenty of people wander in such places and get little more than a rash, as the Vashta Nerada are only strong enough to consume a layer or two of skin. In most cases they are only numerous enough to hunt the remains of other animal’s kills, or the slower moving, older animals. It is easy to identify the places they exist in greater numbers, as the area will be curiously devoid of animal life. When they exist in vast numbers, few people ever return to tell anyone else what the signs of their presence might be.
While they behave very much like any other carnivorous animal, Vashta Nerada can be quite intelligent. Each swarm is a hive mind and they work best as a pack. Like cells in a brain, the more Vashta Nerada are in a swarm, the more intelligent the swarm will be. So, in small numbers, they have little more than animal cunning and a need to feed. Not only are they more physically dangerous in a large swarm, they are more cunning and clever in their hunting patterns.
As they are not usually found in large numbers, the Vashta Nerada must hunt carefully. They do this by mimicking the shadows, or hiding in shadows being cast. They generally move quite slowly but when they manage to attach themselves to a victim they do so physically. So, while you might outrun a shadow that is growing towards The ‘Shadows that melt the flesh’ don’t really need any specific statistics. They are a force of nature rather than an alien you can fight off. In game terms it is easier to think of them as an area effect weapon than a living being. You can’t even negotiate with them unless some piece of technology or advanced psychic power is available, making their Presence immaterial. They fear little or nothing (although the Doctor’s reputation gave them pause) so Resolve is no use.
Their Ingenuity is dependant on the size of the swarm but even so they will only be concerned with eating and hunting. However, Awareness can be used to determine if the Vashta Nerada have noticed you and Coordination to decide how long it will be before they get to you. Once you have a second shadow attached to you, then you cannot escape it. At that point it is just a matter of time until the Vashta Nerada attack. Luckily, a second shadow need not mean imminent death, as the Vashta Nerada are opportunists. They are always looking to attach themselves to fresh prey, so when they are hungry again they have a meal ready. Unfortunately the ‘Piranhas of the Air’ don’t stay full for long.
Given their voracious appetite, and their lack of natural enemies, the Vashta Nerada population on a planet often grows to large numbers. Some alien species have developed chemicals that destroy them but you can never be sure you have destroyed them all. When the swarms can find nothing else to eat, they return to the trees to lay spores. The better-fed the swarm, the more spores they can lay. The adults then die off and the spores hibernate until the food source has replenished. Upon detecting the return of life to their location, the Vashta Nerada spores hatch and swarm again, ready to devour everything in their path.
The spores are extraordinarily resilient to damage while hibernating. Their trees can be cut down, pulped, treated and turned into books and the spores will still be hibernating and waiting. So beware, even this book you are holding, or perhaps the wood in the chair you are sitting on, may have come from a forest of the Vashta Nerada. The microscopic spores may just be waiting for the time to hatch. So always read in the light and if you remember nothing else, always count the shadows, and if the shadows move, run.