Editing Setting:Brighthammer 40,000/Warp Horrors (section)

=== The Wanderer of the Warp === 
''Alias: The Oldest Brother; Spirit of Shadow''

The Wanderer of the Warp is a ancient Horror; possibly one of the few remaining of the Great Old Ones' original servants. It is encountered maybe twice every millennium, but some of its appearances have been well documented. It may appear when a summon of an Order Daemon is improperly warded, gradually superimposing itself over the Daemon until it gains access to the Materium in its stead.
Its appearance varies; generally, its body appears looking like one of its summoners, replicating clothes down to insignificant details; however, the Wanderer's body does not emulate flesh but solid shadow.
Terribly powerful, it has been known to immediately attack its summoners, not stopping until a sufficient level of destruction has been inflicted. It has been observed to immolate its victims, as well as turn parts of its body into piercing weapons.
While powerful, it can be defeated and sent back into the Warp; in one notable encounter, the Primarch Rogal Dorn single-handedly fought it to a bloody stalemate until it retreated through a Warp portal, clearly weakened by the encounter.
The Adeptus Telepathica theorizes that this Horror is a manifestation of man's desire to hide his darkest secrets from himself.