Supreme Throne

"Malik el Sami: "You shut yourself in the Shattered Keep—"

Cyric: "Castle of the Supreme Throne!"

Malik: "—and delude yourself into believing you play other gods like puppets."

- Exchange between Malik and Cyric in a farm near Candlekeep

The Supreme Throne was a Fiendish plane in the World Tree cosmology and an Astral dominion in the World Axis cosmology. Its only standing structure, the Shattered Castle, also known as the Shattered Keep and the Castle of the Supreme Throne, was the divine realm of Cyric, the Prince of Lies. Following the murder of the Goddess of Magic, Mystra, the realm also became Cyric's prison, by the hands of fellow gods Lathander, Tyr, and Sune.

Cosmology
According to the Great Wheel cosmology, the Shattered Castle was a realm within Cocytus, the second layer of Pandemonium, after Cyric retreated from his previous realm of Bone Castle in Hades.

Geography
Much like the rest of Cocytus, the Supreme Throne was a barren realm where howling winds could drive mortals mad. Because Cyric was the enemy of all other faiths, the followers of any deity besides Cyric found their spells more difficult to cast on the plane.

The Shattered Castle was a twisted and ruined fortress that first served as Cyric's seat of power, and as his prison afterwards. It was called the "Castle of the Supreme Throne" only by Cyric himself.

History
According to a thrall captured by mind flayers of Oryndoll beneath Andalbruin, the Supreme Throne was originally established as a kingdom in the plane of Limbo by batrachi who had left Toril after around −31500 DR. There, the deity called Ramenos once again changed the batrachi to serve his goals.

The Shattered Castle was then moved by Cyric and brought to Pandemonium as he retreated to that plane after reading the Cyrinishad in the. Cyric, driven mad, abandoned Bone Castle in Hades and established his new realm in Cocytus as a twisted, ever-changing fortress, which served as his base from where he hatched his plans to conquer Toril.

In the, after Cyric murdered Mystra and triggered the Spellplague, Lathander, Sune, and Tyr decreed that Cyric be imprisoned in the Supreme Throne for 1000 years.

Inhabitants
The Supreme Throne was the home plane of chaos beasts, demodands, howlers, and slaadi. It was also home to howling dragons and chaos dragons.

Since its inception in Limbo, the realm was inhabited by batrachi. Among them was Bazim-Gorag, the Firebringer.

Rumors & Legends
A rumor existed that seven black iron keys were required to free Cyric from his shackles within his prison.