Yu'Vath - Artefacts of Doom: There are two primary reasons for this attitude. The first is that many of these devices are capable of direct interaction with the Warp. Virtually all of the surviving artefacts rely upon a constant connection to that unnatural realm as their primary source of power; some go a step further and utilise this unholy association in their core function.A few might serve a relatively useful and minor role, such as warning of a presence within the Warp or monitoring the nearby region of Warpspace for any anomalies that might cause difficulties in travel and communications. Others, however, have far more dangerous interactions such as unleashing vast quantities of Warp energy in unpredictable patterns, presenting a beacon to Warp entities, or even opening a portal to the Warp.The second major blasphemy of Yu'Vath technology is that much of it incorporates synthetically constructed spirits. Unlike the blessed Machine Spirits that dwell within all sanctified Imperial technology, these entities are unliving creations of the extinct xenos.Those few Tech-priests who willingly speak of these devices mention that the spirits may be daemonic essences captured from the Warp or simply unholy creations that have grown more malicious over the millennia since their creation.The fools who dare to tamper with these artefacts are often influenced by the dark spirits to perform actions that could damn their minds and souls. Some may unwillingly establish a close relationship with the Ruinous Powers, while others might simply destroy themselves and all they hold dear as the devices subsume their minds for their own dark purposes.These two combined dangers represent a significant threat to even the best-trained members of the Adeptus Mechanicus. For those without such a background, these objects pose an even greater danger. Many of the Yu'Vath artefacts become active the moment that a sentient being approaches. More than one Inquisitorial report begins when a single undisciplined individual acquired and activated such a device without even realising that his mind had already fallen under its influence.In many cases, such artefacts pose an even greater threat aboard a vessel that travels through the Warp. It is for this reason that so many Rogue Traders who dabble in the Cold Trade have become lost. These xenotech creations already interact with the Warp directly, and some create a portal through a vessel's protective Gellar Field. In the presence of a Warp Storm, this pinhole can sometimes offer hostile entities access to the vessel's interior with predictable results.Of course, for some individuals, the rewards offered by these potent artefacts more than offset any risks associated with them. Legends tell of Yu'Vath devices that could transport planets through the Warp, provide limitless energy, or even extinguish stars. More modest examples are clearly capable of reading and controlling minds or slaying a sentient in countless subtle ways.A single device, if used effectively, could make a person unimaginably rich or save a planet from the brink of starvation or ecological destruction. These blasphemous constructs harness unbelievably potent forces in efficient and effective manners. It is not the devices that pay the price for their use however, it is instead the users who dare to work with the artefacts knowing that it may cost them their souls.A few Rogue Traders have discovered Yu'Vath vessel components among the Space Hulks that drift within the Koronus Expanse. While rare, these devices often enhance vessels in ways that are not in keeping with the Imperium's understanding of science. Voidsmens' tales include Yu'Vath engines that can allow a vessel to complete a Warp transit at shocking speed, travelling from one end of the Expanse to the other in moments.Other stories recount shields that are utterly impenetrable and weapons capable of shearing through a Battleship in a single salvo. Yet virtually all of these stories tell of the dark price that the vessels paid for their use. Those voidcraft which were not lost during a Warp transit were inevitably soon populated by crews driven mad by the components that had once seemed their salvation. When Imperial technology breaks down it is typically only inconvenient or deadly. When a Yu'Vath component fails, the ship and her crew may suffer fates far worse than mortal death.A few known Yu'Vath artefacts pose a substantial individual risk in that they graft onto the owner when used. Such devices clearly represent a xenos analogue to cybernetic devices. Imperial cybernetic replacements are typically only installed at the patient's discretion; most often after a loss of a limb. These unholy creations are capable of completely subsuming a user's organs when first activated.Astropathic observers have even suggested that just as the artefact merges with the individual's body, so too does its mind and soul fuse with the wielder's. Most immediately die during the process, as the devices attempt to interact with neurophysiology that is clearly at odds with their original design. Those who survive the process may be changed as the unholy synthetic spirit attempts to seize control of their body.At least three anecdotal reports indicate cases where what started off as a handheld device eventually completely replaced the user's body with a bony exoskeleton, devouring the body and the mind to drive it towards a task that had been pre-programmed millennia in the past.Interestingly, some of these devices seem to physically grow in size and capacity as they are used. Ancient tales suggest that such expansion in capacity comes as they devour the wielder's soul. Better-documented reports from the Angevin Crusade indicate that this may actually be an inherent part of Yu'Vath manufacturing. Some reports from the time of the Crusade suggest that with sufficient use, some of these artefacts actually produce functionally identical devices.In this way, a critical ship's component might grow its own replacement part or a device that served a frequent need might be duplicated and spread throughout the Yu'Vath Empire. In spite of these tales, it remains rare to find identical Yu'Vath artefacts.It may be that these duplicates are not as capable of preservation or it may be that over the millennia the original device somehow absorbs them once again. Without confirmation and analysis by Adeptus Mechanicus agents, the Ordo Xenos retains only a limited understanding of those unknowable creations it has seized and destroyed.