The Empress Kadaena (Iruaric: "Empress", "slayer") was the last ruler of the imperial line that ended the First Era of Shadow World history. The K'ta'viiri family (Ir. "Lords of Essaence") were an extremely powerful group of humanoids on the scale of demi-gods, until a civil war broke out between Kadaena and her rebellious cousin Utha, who wished to end the wanton destruction of her wicked rule. The war was begun as a result of Kadaena performing extreme extra-planar experiments on Charon (Lornon), forging an artificial plane that was coexistent with the moon, which she used as a hidden keep to invent her hideous monstrosities. Utha was the father of Andraax, who founded the Loremasters and Library of Nomikos (Biblia), and slayed the father of Lorgalis in the Second Era.
Kadaena was almost invincible due to the Shadowstone, an immensely powerful artifact she wore around her neck. It was a soul devouring necklace that even the gods feared, which Ondoval recovered in the Third Era. She had a vast army of dark races such as orcs and trolls which she had created through foul experimentation, as well as constructs she invented including the gogor (vruul), and hordes of demonic entities from other planes of existence or her own making. The servants of the Shadow were said to have created the first of the Great Demons, and Kadaena was known to use Ordainers and "Flamesoul" fire demons as bodyguards. Some Loremasters even speculated that the Dark Gods may have first come into being as Lord of Essaence experiments with creating non-corporeal life.
There were very few survivors, both sides were almost wiped out. The world was virtually destroyed. Finally, Utha decapitated Kadaena with a sword specially forged to counter the Shadowstone, with one account holding her body fell through the Gates of the Void. The Void was sealed with two powerful gemstones floating over ornate pedestals, one at each pole of the world, called the Eyes of Utha. The Ahrenreth sealed errant portals and vanquished rogue demons for thousands of years while the world healed, with the Lords of Orhan (Liabo) eventually repopulating the world with races they had saved on their moon. The surviving Lords of Essaence slumbered in stasis for the next hundred millennia, discovering the world teeming with intelligent life to their surprise when they began waking up.
Kadaena had a daughter named V'rama Vair who regained consciousness in 2000 Second Era. Her father was a slave named Eogun who hid her for fear Kadaena would kill her upon discovering her mortality. She ruled an island in south-west Jaiman that had been a stronghold of Kadaena, under the patronage of the dark goddess Orgiana (Eorgina) whose identity was conflated with Kadaena in their culture. Her rule ended shortly after the I.C.E. Age version of Eorgina was banished to the Black Hel by the Lords of Orhan in 6800 Second Era. The Dark Gods returned to the world early in the Second Era, and were forced back to Charon (Lornon) in the archaic history at the end of the Wars of Dominion. Her surviving followers, such as Lorgalis, worked with them and servants of the Unlife.
Behind the Scenes
Though no one corresponding to Kadaena per se exists in Elanthian history, Eorgina strongly resembles her, and was given her role by unleashing the Ur-Daemon on the Drakes. In fact, Eorgina much more closely resembles Kadaena in her most recent incarnation than her own I.C.E. Age precursor, Orgiana, the male-hating flame goddess whose cults tortured and slaughtered men. Within the Lovecraftian subtext of The Graveyard is the idea that Kadaena had the power to see the future, including her own death, which combined with a certain apocalyptic disposition may be the basis of Gosaena as a prophetic death goddess on the other side of the gates. (Her original post-I.C.E. Age theology was simply "an evil local goddess.") While the Gates of Oblivion and possibly the Lake of Tears were on the moon of Orhan, the lake is now located next to the Eye of the Drake which is the analog of the Gates of the Void, and the Ebon Gates are now implicitly associated with Mount Aenatumgana.
The juxtaposition of Eissa (Lorminstra) and Empress Kadaena on The Graveyard gate would have been considered blasphemous in its original context, effectively saying souls are "lost to the demonic" (meaning the Void) rather than eternal peace through the Gates of Oblivion. It requires interpretation as it makes no inherent sense. The Void was the one key that "must never be used" on the Gates. The Graveyard gate appears to be in flames due to the corrosion of iron, symbolizing The Black Hel with Kadaena as the "Guardian of the Forbidden." The false sarcophagus of Kadaena in the royal estate on that isle guarded the actual portal leading to the Black Hel. There were six locks sealing this portal, and there were six keys to Oblivion. Hence, the Phantom Gatekeeper, mocking Eissa.
While the first age cataclysm in the modern Elanthian history was different from the Lord of Essaence war, the Void and Eyes of Utha were essentially the same as The Rift and the Eyes of Koar. They were designed to shield the world from the radiations of the inter-dimensional rift, subdue Flow storms, and prevent easy access by malevolent extra-dimensional entities. They also made the Eastern hemisphere inaccessible, which is not true in Elanthia. The southern Gate of the Void was guarded by the true sarcophagus of Kadaena, controlled by Lorgalis as a fortress of the Jerak Ahrenreth. The presence of her headless body near the South Pole has the added relevance of the material world version of the mountain Kadath being located in Antarctica near the South Pole. The Old One telepathic race of "The Mound" which backgrounds Shadow Valley was from there once, while "At the Mountains of Madness" and "The Dream-Quest of Unknown Kadath" do so for The Broken Lands.