The wheel of Worlds

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Source Book of the Damned Volume I: Princes of Darkness 49
Description
Within the Wheel lie all possibilities and none, and while those who use it touch countless worlds, their destinations are the same. At first glance, the Wheel of Worlds appears as a masterfully crafted spherical astrolabe approximately the size of a human skull. Rings of bronze, steel, and dark adamantine form a shifting shell, and as each band moves it reveals another below. These rings each bear minute spidery symbols, marking and measuring the location of thirteen planets, countless stars, and the celestial spheres beyond. Many researchers who have obsessed over the device claim that within lies the truth of the Heavens and beyond. Most realize too late that the truth they seek is not one any mortal should know.
The Wheel of Worlds creates gates to other planes. Using it causes a portal to open to a random plane for 1 minute (roll on the adjacent table to determine the destination). The portal is not transparent, preventing a view of the plane beyond, though the Wheel’s user is given an impression of it. The user may then either travel to that plane or call through a creature native to that realm. Doing either immediately closes the gate. If the bearer wishes, he may attempt to open a portal to a specific plane by manipulating the rings of the artifact, a complex series of adjustments requiring a DC 25 Wisdom check. Failure on such a check by 5 or less still results in a random roll on the planes and layers table, but the Wheel’s user can select whether the destination is that plane or the next or previous plane listed on the table, granting some inf luence over the gate.
But within the Wheel of Worlds lies a trap. Every time a wielder uses the astrolabe, its rings collapse and reveal stranger, more profane markings within. The GM should track each use of the artifact. After every portal opened there is a cumulative 1% chance that next time the portal is used it opens not to the randomly generated plane, but to the corresponding layer of Hell noted on the chart. Every attempt to influence the plane to which the Wheel opens a portal (whether successful or not) increases this chance by 3%. In such cases, the wielder is given a wrong impression of the plane beyond, believing the gate has opened to the expected plane, rather than a part of Hell. If he attempts to summon a creature through the gate that is not a native of Hell, a random devil is conjured. This devil is not under the user’s control and attempts to drag the user back to Hell with it. Every creature who uses the Wheel of Worlds has its own percent chance of this diabolical malfunction that can never be reduced. Should a creature ever reach a 100% chance of opening a gate to a layer of Hell, the Wheel of Worlds instantly shifts both itself and its wielder to a random layer of Hell upon its next use.
1d10	Plane	Layer of Hell
1	The Abyss	Avernus
2	The Maelstrom	Dis
3	Axis	Erebus
4	Nirvana	Phlegethon
5	Elysium	Stygia
6	Heaven	Malebolge
7	The Boneyard	Cocytus
8	Abbadon	Caina
9	Hell	Nessus
10	Roll Again	Roll Again
Throne of Ydersius Ascendant