By User Zimrazim
[Because I love eeeeeevil, corrupting artifacts. If one of your PCs managed to get ahold of this artifact in a campaign, would he/she be able to resist the temptation to use it? 'Just once?' It can't be too bad if you use the artifact just once, right? And hey, it worked so well the last time, why not use it just one more time?]
'The methods used to forge Secret Keeper are themselves quite secret and undoubtedly highly valuable. What could be so powerful as to reveal things that even yugoloths don't know? The distilled essence of a dead God of knowledge, or perhaps a Power of secrets? The souls of corrupted clerics of said Power? A shard of something older than this universe? Or something else entirely?' -- Jultas Kho-Shemor, sage.
'Cutter, are you seriously telling me that both sodding Demogorgon and the Dark Prince are turning half the plane into a bloody ruin over something so cursed frilly as this thing?" -- A tiefling, upon viewing a disguised version of the artifact.
While functional as a powerful enchanted weapon, it is not for this reason that Secret Keeper is so sought after by fiends and mortal beings alike. Its true appearance is that of a tessen or war fan, of a dark grey metal much stronger than mere steel. Highly artistic, ever-changing designs flow across the fan's surface, depicting scenes and images that are intensely disturbing to the viewer. There are a few occasions in the history of the Blood War where it has been used to injure or even slay fiends, celestials, and other beings. It is known to have the property of wounding when so used, and wounds so caused are very difficult to heal, requiring major quests to do so (if a method can be found at all). The fan is perfectly capable of disguising itself as a variety of nonmagical, often quite decorative fans, though bringing it into the Upper Planes or onto holy ground dedicated to a good-aligned deity will force it to assume its true appearance.
Another of its minor functions is its usefulness as a signaling fan: the artifact is capable of sending silent, magical messages across very long distances, though not between planes, when prominently displayed. Secret Keeper has been observed being used to coordinate the movements of Blood War armies a number of times, and even mortal adventuring bands and mercenary groups have been known to use it in this fashion.
The first known tale in which Secret Keeper appears involves a mortal human woman on some otherwise unremarkable Prime Material world. A mere concubine, of great beauty but humble birth, sought greater and greater power for herself. In time, a 'human' tinkerer managed to impress the locals of this portion of the world with minor magic tricks and clever, entertaining devices. Eventually he managed to meet with her, and offered her what he knew she wanted most -- the power to unseat the wives and concubines between herself and the king. If, when she was alone, she would hold the fan like so and whisper specific words to it, the fan would show her scenes, animated on its surface, of whatever dark, scandalous secrets the concubine's rivals had. She would also be able to use it to send secret, silent messages to her own servants. Delighted, she offered to arrange to get him a position at court, but the 'tinkerer' politely declined, replying that he would prefer to wait to be rewarded until after she sat upon the queen's throne.
After that meeting, the higher-ranking concubines and the king's wives began to have very bad things happen to them. Their own secret plans began to go badly awry. One was executed for having an affair with one of the king's male relatives; another was executed for plotting to have her own son take over the throne. Another took her own life, while yet another removed herself suddenly from court intrigues. It was not so long until the concubine was elevated to the status of wife and sat upon a throne beside the king, just as the 'tinkerer' had predicted.
She came soon enough to rule the land through the king and her own sons, and it was by no means a gentle reign. After several years and the king's death (actually in a war of conquest far away, not as a result of the concubine's ambitions), the curse of the artifact made itself felt: one of the concubine's own secrets became known. Her eldest son had not been sired by the king, but by another man. The queen was hanged, the eldest son was killed, and the realm was thrown into a war over the now-uncertain succession.
The artifact has appeared in many times and places since then. Rumor holds that it can be handled safely once, or a few times... just how many times is never clear... without suffering eternal damnation. The stories agree that repeated use of the artifact by a mortal will eventually bring about that mortal's destruction by revealing some important secret of his own to his enemies, and his soul will end up in some dire realm -- most likely Gehenna, considering the nature of both the device and its creator. Its effect on fiendish owners seems to be somewhat different. The artifact's curse, that of revealing some secret of the wielder's, does not seem to happen to an immortal wielder, but fiends tend to regard the device as dangerous and fickle to use. Many of its fiendish long-term wielders do seem to come to a variety of bad ends... but others seem to obtain great power, only to have the artifact disappear on them.
The most recent wielder of Secret Keeper was a powerful marilith and noted Blood War general whose given name was Ithis-Krassika. She used Secret Keeper to gain as much tactical information as she could concerning the plans of enemy baatezu commanders. (The artifact is notorious for being able to overcome or bypass most forms of anti-divination, magic resistance, or the like when it comes to its primary function.) Ithis-Krassika also used the artifact to coordinate her own troops (to the extent that tanar'ri can be coordinated at all). She is believed to have been recently killed during the course of a major Blood War battle on an obscure layer of the Abyss, and the current whereabouts of the artifact are unknown.
Secret Keeper is known to have been forged by an arcanaloth, and it appears to be impossible to use the artifact against any yugoloth. Attempting to use its divinatory ability against a yugoloth will result in Secret Keeper providing convincing yet false information to the wielder. If the yugoloth is disguised in some way, the false information provided is even consistent with the 'loth's false identity. It is also rumored that yugoloths are unable to use Secret Keeper themselves, and instead manipulate others into using it if they wish to glean information from the artifact.