Umbra

The Umbra were an alien species that existed within the galaxy.

Appearance wise, it was revealed to be a black sphere but this masked its abilities as it possessed the capacity to manipulate the very shadows as weapons. They were known to be warp related creatures and were often sighted near starship engines.

With an ability to manipulate shadows, these creatures show a direct aversion to light. Experiments performed by Magos Biologis Sharle Darvus have demonstrated that containment within an area lacking any shadows was sufficient to euthanize the creature.

One theory put forward by Calculus-Logi Byrr is that the physical form of the umbra is but a small refection of the whole creature, with the rest existing in another dimension other then the prime material. This could help to account for the creature’s ability to manipulate and control “shadows”.

Upon death both Magos Darvus and the accompanying Inquisitor experienced “intense cranial pain, a flicker of images (a humanoid figure splintering apart, warpstorm, deep space), and a single word: Linger”. This seems to denote some psychic ability, even if it is limited. Questionable text penned by a self confessed heretic speaks of a “war in the heavens between star devils and old gods” Likely the C’tan and Old Ones. After all the Old gods were killed one survived and hid in the warp. Then “She’s born in the longears’ brain”, Slaanesh, “chops him a million times and kicks the shards out into the cold. To Linger, she says to linger like always”

These descriptions could be considered consistent with the visions experienced by Magos Darvus. This would suggest that the Umbra are a fragment of a greater entity, perhaps one of the old ones or some other unknown warp entity. Noting that they are often found attached to warp engines or in area’s suspected of being entrances to the Eldar Webway may denote an attempt to return to the warp.

Perhaps these stories relate to the battle between Slaanesh and Khorne over the fallen Eldar god Khain, where he was split into a thousand pieces and sundered across the galaxy.