The eve after a great battle, the restless dead begin to rise from the corpses of those who are left to fester upon the battlefield. Alongside the deaths, there is also the memories, and the trauma. It's said every soldier leaves a part of themselves on the battlefield. These memories are left to fester with the corpses. No one spends the time to clean them up, only hide them, but these traumas have the power to end kingdoms, destroy cities, change the course of history. The echoes of these trauma don't just live in the hearts of the survivors, they remain haunting the battlefields.
These spectral echoes of battles look like small emaciated people, with overly defined features, showing the traumas they were born from. Many will have horrible wounds, grasping claws from the final rending of flesh, horrible teeth, or other grotesquities. They glow with a strange green or yellow light, and they are spectral, being untouchable, and untouching, but they can be felt due to the fact that they are icy to the touch. While they often seem like the are spirits of the restless dead, and very commonly confused for them, they are not in any way the restless dead, having no personality, simply the single traumatic event they are born of.
These spectral echoes tend to gather together into large swarms if they are left unattended. This means that most religions have a method of blessing battlefields to attempt to dissipated these beings, and if they are not obeyed, nearby people are often attacked by a swarm of specters, attempting to reenact the violence that birthed them. Before they have banded together, these echoes will haunt the place of the horror the birthed them, often staying within a few meters, and it's only if they are chasing a person they are terrorizing will they begin to find other echoes created by their battle. Typically a battle will create less than a score of true spectral echoes, usually only one in a dozen people on the battlefield or so.
Swarming: Spectral Echoes, like all trauma, want to gather together to become an unconquerable swarm. If Spectral Echoes gather together they can become incredibly powerful very quickly. If a swarm begins, the Spectral Echoes count as a single entity, but they can Engage with multiple foes in Fight. If they are engaged with multiple targets, they must all script using the same action - but their effects affect everyone who they are engaged with. If the swarm is in the order of dozens of echoes they can quickly destroy several enemies. Secondly, when they take a wound, they simply lose a member of the swarm instead of taking any wound (even superficial), representing the swarm slowly being destroyed (keep in mind the Echo's spirit nature making it hard to harm them).
Traumaborn: Spectral Echoes are born of trauma. They are specifically linked to a single trauma that birthed them. Blind fury, brutal murder, unrivaled terror, and horrible crimes, things so horrible that they stand out as brutal, even on the battlefields. Spectral Echoes desire the feeling that birthed them. They will typically try to cause horrible terror or bloody violence, or worse, in order to remain comfortable and happy. This means they seek out those who can feel these horrible emotions, and attempt to cause them.
Witchlight: Spectral Echos give off an aura of ghostly light which makes it easy to see them, but hard to see. Treat all light near the Spectral Echo or its Swarm as Dim Light. All additional light sources (except the sun) do not help, because the light is being dimmed by the swarm. If the sun overpowers their light, the Spectral Echo immediately takes a Mortal Wound. But they are smart enough to hide from the holy and the light.
Icy Aura: The Spectral Echo has an icy aura, which can be felt for a few minutes after the echo passes by. This allows them to be tracked even if they do not leave marks. This also is a common way for lone echoes to terrify those who wander too close, racing around and causing cold spots, while remaining in hiding.
Terror: When the Spectral Echoes attack someone they do not deal traditional damage. When the echo uses the Strike action they may roll Savage Attack with WS - Add 2, but instead of ordinary damage they set their IMS using their Will. These wounds cannot be prevented with armour, and they cannot be healed properly. They do not deteriorate, but when the wounded next takes a meal and shares tales with friends, they may attempt to Treat the wound. Use the person healing's Steel as a treatment skill, success and failure as normal (including potential immediate deterioration). There is no treatment penalty for the damage type.
A Burning Wheel Monster Every Week