Dark Heresy, Radical's Handbook, p. 175
Occult Artefacts
the lens of seeing
This artefact appears as nothing more than a simple monocle, similar to those worn by the aristocracy across the Imperium. Close inspection will show the lens itself is made from the finest crystal, with none of the usual marks left by mechanical polishers. The frame is gold wire, engraved with tiny symbols and sigils, and comes with a length of fine chain so the lens can easily be attached to one's clothing.
A curious and almost benign artefact—unlike many creations of the malefic arts—the Lens of Seeing was in fact shaped by the Radical Inquisitor Immel Amud. He sought to use it for the Imperium's benefit, seeking a way to decipher the oft-encoded tomes found in the possession of cultists and sorcerers. For a time, the Lens proved to be a valued tool in his crusade against the forces of Chaos, allowing Amud to clearly read even the most minor of notes, thus laying the cultists' plans out in the open to be countered. But eventually the fickle nature of the warp made itself known, and Amud discovered far too late the price the Lens asks for its services.
Driven to near madness by his obsession with secrets the Lens revealed, Amud met his end when a supposedly minor gathering of cultists proved to have ten times that number. Slain in the ensuing battle, Amud's body was eventually recovered, but the Lens was not to be found.
using the lens of seeing
Activating the Lens requires an Ordinary (+10) Invocation Test and a Full Action. Once the Lens has been activated, it will make any text viewed through it legible to the character regardless of origin. This includes text written in various xenos tongues, ciphers, codes, and the like. The effect lasts as long as the character reads one particular text. If he switches to a new book, he must reactivate the Lens.
The Lens, while quite useful, isn't without its hazards. Each individual use of the Lens causes the character to gain 1 Insanity Point. Keep this total separate from any other Insanity Points the character may gain. Once the character gains 10 Insanity Points from using the Lens, he must make a Trauma Test as described on page 234 of the Dark heresy Rulebook. However, failure doesn't result in a roll on the Mental Trauma table; it simply reflects how much control over the character the Lens has.
As the character gains Insanity Points (and potentially fails Trauma Tests) he becomes more and more possessive of the Lens, until eventually he will refuse to be without it. In addition, once the character reaches 40 Insanity Points, he will double-check all written documents with the Lens, looking for hidden meanings and secret messages. Once he reaches 60 Insanity Points, he will only read documents via the Lens, and once he reaches 80 Insanity Points he will have lost the ability to read anything unless using the Lens. In addition, once the character has 60 Insanity Points and is totally dependent on the Lens, the accursed monocle will begin to alter the content of whatever the character is reading, subtly changing words and sentences.
Personally I think the mechanics for it are too harsh, too much of a deterministic doom spiral. I'd switch things up, make it so the insanity gain only applies on a
invocation, and is 1d5-2 (min zero) - or maybe something based on degrees of failure - instead of a flat 1 per use. Variable invocation difficulty based on how much actual hidden content there is, too. That way, there's a "preview" of the endgame distortions, and somebody with the right sort of hubris can think to themselves "aha, so I just need to max out my stats for that invocation roll," and routinely checking innocuous documents can actually make some OOC sense, but eventually they'll come across something with an extra-nasty stack of hidden layers and get a bad roll at the same time.
