d20 Treasures Not From This World
Disclaimer: This is a mildly expanded & refurbished version of a post on my old blog, which I was eternally unhappy with.
Today's theme is otherworldly entities, ranging from outsiders to undead to souls, it's not a very strict theme, you see. They're also not written with any balance intended, so tread carefully.
01 Singing Crystal Shard
A peach coloured crystal shard the size of a dagger. If struck like a tuning fork, it produces a bright, clinking sound. If struck while stuck in the flesh of an outsider, the shard instead emanates a keening pitch that forces the outsider to succeed on a save or be banished to their home plane. The shard has a 1-in-6 chance of shattering on any attack roll (even on a miss, it might hit armour or be blocked by the outsider).
02 Cosmic Nail
The Cosmic Nail is really just a splinter of meteoric iron, iridescent and viciously edged. If stabbed into a creature, it stops any and all plane shifting magic from working on that creature, anchoring it to the current plane. Even teleportation magic within the same plane has a 5-in-6 chance of failing. Instead, the target will feel tremendous pain as the magic pulls on flesh that's essentially nailed in place (in plane?) by the splinter. The victim can try to pull the Nail out, but will take damage in the process from cutting its hands or appendages on the splinter's edges. Normal movement, i.e. just walking to another place, isn't inhibited, even though it might very well be rather painful to walk around with a jagged piece of metal the length of a human forearm stuck in your intestines.
03 Orb of Sealing
A perfectly smooth sphere of black liquid with colourful swirls in it, floating a hand's width above a marble pedestal. These Orbs are used to contain a being's powers and to hide them, until either a later return or the opposite, to prevent a later return. The Orbs are enchanted against scrying, so an angel won't be able to scry the location of an evil's power, nor will a lich's devotees easily re-discover their master's might. Faced with millennia however, the seals often prove too weak and energies leak out. Not enough to be detected from afar, but plenty to corrupt whatever's nearby: the crypt, the fauna aboveground or the cult protecting the Orb. To reunite a creature with its powers, it simply has to touch the Orb to its material body. Any other creature touched by such an Orb will inevitably die a very painful death, either torn apart right away, sucked into the pocket dimension inside the Orb or taken over by the sentience that often inhabits those Orbs.
04 A Bottle of Crab
A bulbous, earthen bottle covered in barnacles and kelp. If the glass stopper is removed, a steady stream of thumbnail sized crabs spews forth, about three litres every round. Each round, roll a die, starting with a d12. If you roll a 1, downsize the die to the next lowest die (d12 > d10 > … > d4). Rolling a one on the final die means the bottle is spent, for now. It cannot be stoppered early. The bottle can be refilled by submerging it for the night in the sea during spring tide. If the bottle is broken, it violently erupts into 4d4m³ of crabs.
05 Fiend Folio
Pages made from leather, cloth, and even thin slate slabs, bound by two wooden covers, shut with an iron clasp. Each page details a specific demon or devil or similar: A description in varying detail, often accompanied by a sketch, and most importantly the true name of the being. The covers are wooden with an iron clasp, inlaid with protective enchantments against elemental damage and scrying. To unclasp the book, one must swear an oath on their life to never share the folio's contents with anyone, not even vaguely. Sharing that it exists or that one has it is fine. Handing it to someone else is fine. Still, the Folio is sometimes found in rooms full of people dead of no obvious cause. Depending on your setting, true names might compel demons and devils to do the speaker's bidding. Or, they could be used to banish those beings back to their place of origin. The beings listed in the folio naturally will do everything in their power to seek out this folio—if they learned of its unearthing.
06 Seeing Salve
A coin-sized metal locket adorned with a stylized eye, containing a translucent, oily salve with an acrid smell. If you rub the salve into your eyes, you can see extraplanar beings in their true form, like angels disguised as mortals. It doesn't work on entirely material targets that are merely shapeshifted, like a druid turned into a beast. The user can also see if a person is possessed, by a vengeful spirit for example. Because summoned creatures leave a kind of trace in the astral planes, the salve may also be used to trace those creatures to their point of summoning. The locket contains 1d4+2 uses worth of salve. Using it is quite painful—seeing the world beyond burns in the eyes like staring into the sun. One dose lasts 8h, after which the user must succeed on a save or be blinded for a day.
07 Cleansing Salts
A small packet of folded paper, containing a teaspoon of coarse salt, sweet with lilac. It can be sprinkled onto haunted or possessed things/creatures to force the manifestation of whatever's doing the haunting or possessing.
08 Grave Ashes
A hollowed out gourd, with a broad cork stopper, containing the ashes of the dead. Spread on the ground, it attracts carrion creatures like vultures and vermin. Spread on hallowed ground (like a graveyard), it attracts nearby undead.
09 Map of the Invasion of Yl'Azar
Human skin rolled into a tight bundle. The skin's original owner bore now faded religious tattoos of a good-aligned order of paladins. The skin's inside shows a map of the second year of the demonic invasion of Yl'Azar, showing strongholds and frontlines, sites of battle and humanoid encampments. It could be used to track down holy artefacts lost in the war, or to find a weak spot in the fabric between worlds (the demonic strongholds were usually placed at such rifts).
10 Plane Jumper
The Plane Jumper is a massive carriage of battered and torched oak, with iron plating, arrow slits and mounted crossbow. The harnesses extend to where there should be horses or maybe mules, but just end in thin air. Instead, invisible lobster-like demons are bound to the carriage by geas. If you step close, you can hear them foaming at their mouths, and quietly click their pincers. The demons can cut the fabric of reality and because distances work differently in different planes and they're often folded weirdly onto each other, one can use different planes as shortcuts to drastically cut down on travel time—much to the chagrin of the planes' native inhabitants. The Plane Jumper is operated by a driver eternally bound to it, until either their death or someone else taking over the reins. Usually the driver is accompanied by an entire band of competent caravan guards.
11 Mind Maggot
Encased in a thumb-sized drop of resin is a kind of maggot, bloated and white and slowly throbbing even in its current state. If you swallow the resin drop, it will dissolve and, over the course of a week or so, the Maggot will make its way into your head, where it attaches to the brain stem. In especially haggard hosts you can see the worm sit at the neck, under the skin, just beneath the skull. Mind Maggots feed on nutrients in the bloodstream but also skim off brain waves. They are relatively harmless as long as you eat enough, about twice as much as normal; but they also have a very strong taste for hallucinations and mind-altering experiences: any saves against drugs or mental effects are made at a disadvantage. On the upside, the host gains immunity against telepathic, mind reading or controlling effects of any kind (there can only be one maggot reading your mind!).
12 Compound Eyes
A tall mason jar full of eyeballs suspended in ochre jelly. Normally, the eyes idly stare about, but will all lock onto any movement nearby. The eyeballs are often implanted into humanoids, willing or at least restrained, and with the right mental command one can watch through all synchronised eyeballs as if they were in one's own head. While the eyes are usually humanoid, there is no rule that stops the creation of other kinds of eyes for use in other creatures, even non-sentient ones. All eyes originating from one creator usually share visual characteristics, for example golden irises or a miniscule rune etched into the whites. For a host without the mental command, the eyes still work as their normal eye would, except if you don't actively look at something, your Compound Eye jerks about, inspecting your surroundings on its own. You'll get used to it, but others might find it discomforting.
13 Hound's Whistle
An unadorned piece of bamboo, thin as a twig and as long as a finger, carved into a kind of flute. It produces a sound too high in frequency for human ears, not too high for a canine's, however. The whistle's call magically attracts dogs and hounds within three miles, and while thus attracted canines aren't automatically friendly to the whistler, their reaction rolls are shifted by one to the friendly outcome. But the whistle is also cursed: There is a 1-in-36 chance (snake eyes on two d6) its call pierces the veil that separates our world from the others and instead attracts hell hounds (or similar beings, like fey aspected wolves). If blown at a fateful, magical time, for example during a full moon or near a rift in the planar fabric, the chance is 1-in-6 instead. Any creature called by the whistle once in the past is immune to its compulsion in the future—it'll still hear the call and might decide to heed it, if the whistler fed the creature on the previous occasion, for example.
14 Torch of Torment
A torch of blackened iron, its top fashioned like skeletal fingers clasping the flame. It burns without smoke or smell, but if one listens closely they can hear the screams of torment of the souls held in the miniature hellfire that is the flame—but the screams are easily ignored. The flame produces heat as a normal torch does, but is everburning and can only be extinguished by calling out Silence, Sinners! which snuffs out the flame instantly. To relight it, the torch has to be used to kill a sentient creature, whose soul will be trapped within the pocket hell. Snuffing the flame disintegrates any souls contained in it.
15 The Fracture
An unwieldy but perfect globe the size of a pumpkin, made of some kind of crystal, containing what looks like a black spot. Straight lines near the globe seem to bend ever so slightly toward its centre and light is dimmed around it. The sphere is much heavier than its size would suggest, clocking in at several tonnes. It contains a fracture in space-time, and if it's shattered, all existence within a couple miles will be sucked into it to disappear forever. Atmosphere or water or crumbling stone will fill the remaining void in time, probably.
16 Canopic Jars
Seven earthen amphorae with stylized animal heads, the sweet smell of decay mixed with pungent florals emanating from them. They surround an earthen, life-size statue, crude features drawn on in blood. Linked by powerful ritual magic, if the caster dies, their soul will attach to this facsimile of themselves and reanimate, powered by the will of those contained within the jars. There is a catch, however: The donors, their organs to be contained in the amphorae, must be willing sacrifices, and they must not lose faith in their cause while they await being used. Magic charms and such will do little to sway a sacrifice's opinion of you even in the afterlife, and as such you must impress them sufficiently by mundane means. A cluster of Canopic Jars found is usually long abandoned, the original owner dead for good after failing their sacrifices. Of course that doesn't mean one can't re-use the jars, new donors are required, however, and the spells must be cast anew.
17 Soul Scooper
A wooden spoon, smoothened by use. On an unconscious target it can be used to scoop out the soul, the essence, leaving the body an empty husk. Such husks seem alive to all inspection, but are indubitably dead inside. Necromancers cherish them for they are easily filled with unlife. Un-willed, a husk's only instinct is to prey on the living, clinging to the hope of regaining their own soul by devouring someone else's.
18 Cane of Elemental Authority
A cane's plain silver handle, floating at hip height, above a swirling mass of elemental stuff (e.g. flame, water, mist, lightning, etc). The user is seen as a figure of authority by creatures of the cane's element. Sentient elemental creatures get a save every 24h to resist the cane, a success renders them immune altogether. Elementals of other kinds view the cane bearer as a prime target to topple in an attempt to further their own element's sphere of influence. It's nothing personal. The wearer is immune to the cane's element as long as one hand is on the handle.
19 Planar Anchors
Seven matching piercings of outsider bones. If worn on the chakra points, they prevent any forced movement across time and space like teleportation, banishment, plane shift, or astral projection, including by your own spells. The Anchors also stop ageing, even from magical sources, but getting up in the morning requires a successful save to not spend the day in lethargy, unable to move about much.
20 Void Tree
A seed like a misshapen acorn, black and oily and suspiciously squishy. If kept in absolute darkness, out of the acorn grows a slender trunk, translucent like gossamer against shadows, out of which sprout luminescent, colourless leaves. After a year and a day, if the tree is exposed to a moonless night, vast clusters of flowers open up to the stars, emitting clouds of glittering pollen. For this one night, the pollen joins this realm to the void beyond and allows free transit, but at the first sign of morning, the blossoms and the portal both close forever. Void Trees are usually grown within specially constructed towers, guarded jealously.