The Box of the Deck of Many Things

This is such a pain-in-the-ass item to run, have, or be in proximity to. As a way to reinforce the danger and value of this fuckin' artifact, introduce it before the PCs can use it.

In some goblin's hoard, or something, they find a black box about 6 inches by 4, and 2 deep. The box has a texture like soapstone, with images delicately carved into each face, many now blunted by time.

The box has a clear seam running all the way around it, but can't be opened. Inside is a sheet of lead, about 1/4 inch inside the surface. The box seems to be unbreakable - it's been enchanted as though it were diamond, and sealed with a leveled-up version of arcane lock.

It can be opened in one of four ways:

Cut it open with an adamantine blade. This will take 250 days of dedicated drilling and sawing and work, like learning a new proficiency. It also has a 50% chance to damage the contents, destroying 1d20 cards: roll a d20 - on a natural 1 the contents are destroyed completely.

Use a wish spell. This will pop the lock immediately.

Enter an antimagic field or other magical dead zone. At that point it's still cleverly locked (like a puzzle box) but a complex Int check (thieves' tools would apply) will open it smoothly (3 successes, period 1 hour, on 3rd failure PC can't try again until leveling up).

The "proper" way to open it is to follow the steps outlined on the exterior of the box. Each side features a small vignette with some kind of scene or symbol prominent. If you follow them in the right order - indicated by constellations following each other - the box opens. The scenes include indications that it needs to be held under a waterfall, travel to one of the planes of hell, be placed inside a tree, collect sunlight at midnight, be covered in the blood of a dire beast, and finally have someone cast knock on it. At that point the outer shell falls off, and the puzzle-box underneath is exposed. Unlocking that requires a DC 25 Intelligence (thieves' tools) complex check. If failed this check cannot be attempted again by the same PC until they gain a level.

When the box is finally opened the contents are revealed: a deck of extraordinarily thin ivory plates, about 4 inches by 3. Each one features faded pigments depicting extraordinarily intricate scenes. The edges are chipped, the ivory brown with age. When the panels are tilted back and forth the scenes appear to have depth, as though each were a tiny shadow box. The deck seems to be heavier than the box it came in, hard to lift.

Inside is a scrap of paper, on which a spindly hand has written

'Good luck.'