“Entry: ‘Obscuro’—The nature of the threat is either unknown, resists analysis, is deliberately hidden, or falls outside the normal categories of danger. This threat classification is also in rare circumstances applied to forbidden dangers of mankind’s own forgotten antiquity.”

—Definitions of the Common Inquisitorial Threat Ratings, Tabernacle of the Conclaves Segmentum

The so-called Tyrant Star resists easy interpretation but certain key facts are evident. Komus is described in a doom-laden vision which speaks in apocalyptic terms of a “darkness” that will engulf the worlds of man and ultimately devour human civilization. The engulfing darkness will be preceded by signs and portents, so-called herald events, that will gradually transmute human minds and make them ready to embrace the darkness. Many believe this to be an obvious allusion to a rising of Chaos and the warp, though this explanation is far from universally agreed. There are many considerable threats in the galaxy.

The prophecy could as much apply to the Tyranids (scholars note a repeated use of the word “devour” in the prophecy text) or the Eldar as to the warp. However, given the warp’s manifest ability to uncreate and mutate reality, much weight is given to this idea by the Tyrantine Cabal. The actual text of the prophecy is secured in the archives of the Bastion Serpentis, and Lord Inquisitor Anton Zerbe only allows a very favoured few to examine the complete transcript. In speaking of the herald events, the Propheticum Hereticus Tenebrae, as the manuscript is called, makes many references to “Komus” or the “Tyrant Star”. Komus is said to be the harbinger, a portent of the encroaching darkness.

It is said to be a “black sun” or a “halo of black flame”. This preternatural harbinger is represented by an unholy rune, best described as a clawed bird’s foot. The rune has resisted specific translation and no previous occurrence of it has yet been found. Zerbe believes it can be no coincidence that the Calixis Sector is fraught with a curious, recurring phenomena: that of the “Spectral Sun”. From time to time—no specific interval period has been identified—a monstrous “black sun” matching the prophetic descriptions has mysteriously appeared in various locations throughout the sector. No two appearances have been quite the same but the pattern of visitation is usually this: with little warning, a ghostly star apparently emitting black flames and esoteric, unknown radiations, spontaneously materializes in a planetary system, shines malevolently for a few days, and then, just as mysteriously, vanishes without trace.

The visitation is accompanied by psychic disturbance, geological upheaval and sociological problems, including mass rioting and unrest. Most often, the Spectral Sun actually eclipses a system’s natural star, as if possessing it, causing consternation and panic on the orbiting worlds as their sun goes black. However, the Spectral Sun has also on occasion appeared less directly—a strangely bright star at night, a phantom corona around a moon—before disappearing. No astronomer has successfully explained the eerie phenomenon. It belies human science and has thus far evaded close investigation. Its visitations cannot be predicted.

The Tyrantine Cabal believes that the Spectral Sun phenomenon is the Tyrant Star, Komus, as it so closely matches various descriptions in the prophecy. Some suggest the Tyrant Star is the ghost image of some stellar body in the immaterium, shining through the worn fabric of space. Others say it is a mirror image, a warp-space star that is partially translating into realspace, trying to find a way through. Yet others claim that the Tyrant Star is an artificial body, driven by xenos engines and mechanisms mankind cannot comprehend. Whatever the truth, the phenomenon is a fact. It has manifested eighteen times in the Calixis Sector during the last century. Every single visitation has caused public unrest and geological instability.

Where the Tyrant Star appears, earthquakes and volcanic upsurges follow. A world will experience a violent period of upset and revolution prior to its appearance. Many more psykers than usual will be born or become active. Mutation will occur. These things will usually take place in the two or three months leading up to a manifestation. Signs and portents will be widespread: these generally are a matter of birthmarks, odd runic sigils appearing upon walls without explanation and the rise of fanatical cults. Some sources also describe premonitory half-sightings, fleeting glimpses of the black-flamed sun in mirrors, pools, puddles or even on the surface of wine or water in drinking vessels.

Mass panic and insanity precede a visitation of the Tyrant Star. No one has been able to explain how it appears and covers a system’s natural star with its noxious black smoke. Sometimes, disorder and civil unrest lead to nothing and, for all the portents and cues, the Tyrant Star never actually appears, though this may be because it has manifested in a way that is hard to detect. On at least two recorded occasions, the Tyrant Star has appeared merely as a distant star above a world, no larger than a morning star, instead of eclipsing the local sun. The Tyrantine Cabal believes it is a vital part of its work to trace and investigate these visitations, and to actually be on site to witness a manifestation. Zerbe hopes that important data may be gathered during a genuine sighting. In the sector at large, the visitations are a matter of myth and rumor. The Inquisition has carefully suppressed any official confirmation of the phenomenon.