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.
Kadaena was almost invincible due to the Shadowstone, an immensely powerful artifact she wore around her neck. 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 vruul, and hordes of demonic entities from other planes of existence. The servants of the Shadow were said to have created the first of the Great Demons, and Kadaena was known to use Ordainers and "Flamesouls" 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. The Dark Gods returned to the world early in the Second Era, and were forced back to 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.
The world was virtually destroyed in the cataclysm. Finally, when both factions had been almost totally wiped out, Utha decapitated Kadaena before 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. While the first age cataclysm in the modern Elanthian history was different, these were essentially the same as The Rift and the Eyes of Koar.
Kadaena had a daughter named V'rama Vair who regained consciousness in 2000 Second Era. She ruled an island in south-west Jontara that had been a stronghold of Kadaena, under the patronage of the dark goddess 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 Liabo in 6800 Second Era.
Though no one corresponding to Kadaena per se exists in Elanthian history, Eorgina was given her role by unleashing the Ur-Daemon on the Drakes and strongly resembles her. Kadaena has nothing in common with Gosaena. The juxtaposition of 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" rather than passing through the Gates of Oblivion. The Void was the one key that "must never be used" on the Gates.