Apparition

Apparitions are classified as small phenomena, although, like most disturbances in the shroud, they aren't fully understood, yet. An apparition is any kind of personified vision from beyond the veil that takes on the shape of a sentient being and tries to communicate with the meta realm in some way; usually to achieve the goal of changing something beyond the veil or luring people into the outer worlds. This process is what we call a haunting.
It’s a wide-spread belief in the Crimson Empire that apparitions are actually messages from Lost Ones who try to communicate with their descendants.
The Alliance has their own theories, but the Ordo Scientifica does focus more on destroying apparitions to stop hauntings as on exploring their nature. Some private societies are known to pour funding into research projects to find out more about the rumor that apparitions can lead one into the outer realm and open doors into shards where sunken treasures can be found.
A more complex form of the apparition is the echo. While the apparition is limited to one being, one corpus, one physical appearance, an echo can involve a group of characters or a backdrop scene including environment.

Manifestation

Apparitions take on the form of a person, animal or being, never inanimate objects. But that doesn't necessarily mean the apparition speaks or communicates like something that could be considered human language. Yet they need to have a behavioral pattern that indicates the need to express something or convey a message to classify under the term ‘Apparition’.
They aren’t sentient beings in the usual sense, even though they can be perceived as such, especially by unknowing lambs. An apparition can be more or less complex in their behavior, but will only ever act and speak to achieve one goal; after they did that, they usually disappear. They don’t have any other focus, goal or interest.

Localization

What separates the apparition from lost souls and spectres is the weird fact that they actually don't have a soul. That doesn't make them less unsettling, most of the time, as they can be quite convincing. It also means that apparitions usually happen in the meta realm when the veil is thin. Apparitions can haunt places, people or objects.
Whatever it takes to accomplish their task or broadcast their message, they will do, and some of them have been reported to even take on corporeal form for a limited amount of time so they can interact with the meta realm. How exactly that’s possible is not known. But resonance of the apparition and their surroundings seem to play a vital role in the process.

Type

Metaphysical, Arcane