Arcanum Portentia (arr-KAY-numb poor-TEN-she-uh)

The Arcanum Portentia are a deck of cards similar to tarot that are magic-adjacent in that they are not inherently magical if identified, subjected to Detect Magic etc. but seem tied to magical occurences. Specifically, the cards tend to appear unexpectedly and portend something to come (albeit often in an extremely cryptic way).
It is not known how many cards there are available; Katallo offhandedly suggested 20-25 as a number, but could only verify the specifics of 10 personally. The cards are rare enough that many collectors refuse to reveal how many or which specific cards they own, as there are presumed to be a finite number of them and collecting is a cutthroat game.
The cards feature a series of strange symbols in black on the back along with delicate spiderweb designs (seemingly alluding to The Web). The front of each is without text or numbering to identify them, leading to some disagreements on how to refer to each card, but the designs are typically simple enough to reference based on the single item that is a focal point of each.

by Anthony Gonzalez

Known Cards

by Anthony Gonzalez

The Chest/The Betrayer

An unassuming chest of whorled brown wood beneath the soothing warmth of a torch in an otherwise dark corner.

The Crystals

A nondescript smoky grey background as to not distract from the primary focus: a cluster of crystals with 8 points in the different colors of the rainbow. The colors are vibrant like gemstones and the crystals feel sparkling and shimmering on the bland background.

The Pact/The Accord/The Agreement/The Contract

A long piece of parchment with indecipherable text laid out in blocks or paragraphs with the shadow of a handshake of two humanoid hands looming over the paper but not pictured outright. The card is relatively devoid of color, all the better to render the drama of the red signatures at the bottom, ink thick and running slightly as if in blood.

Manufacturing process

No one knows who made the cards or how their uncannily accurate divination nature is embedded in them. They seem to appear as if with a mind of their own. Of course people make counterfeits but without the strange magical essence of the card the item becomes worthless; a good collector will tell you that you can tell if a card is real by how fickle it is: the more it hops around your store or home, the more likely it is to be real. (Indeed, it is sadly common for someone to realize they had an actual Arcanum Portentia on their hands only by losing it when it "decides" it is needed elsewhere and disappears.)
Dating techniques for the material imply the cards are older than they appear, likely well before The Breaking. (Which is to say it's little wonder they're so valuable and rare; they're paper cards lasting hundreds of years somehow.)

Item type

Miscellaneous

Rarity

Extremely rare oddity, prized by collectors but obscure enough to be worthless to average traders

Dimensions

5" x 3"

Raw materials & Components

The colors are vivid and the cards are a paper-like material that is resistant (but not immune) to water damage, bending and tearing etc. (The value of a card increases the more mint the condition.)