Cor Hydrae is an ancient fortress sealed in another dimension, known as the demonic castle of the evil god Malpercio and the Dark Brethren, the primary antagonists over the course of the entire series. Cor Hydrae is the home for countless monsters and demons who were once human before bartering with the Dark Brethren and unwillingly having their souls and bodies corrupted by their power.
The fortress itself was eventually exiled to another dimension by the Children of the Earth and several humans during a brutal battle occurring some time after The War of The Gods. It serves as the Brethrens' main base of operations where the demons form their plans for war and launch their armies from, as well as where the final showdown between them, in the form of Malpercio, and Kalas and his companions takes place.
Role In The GamesEdit
In Baten Kaitos: Eternal Wings and the Lost Ocean, Cor Hydrae is freed from its separate dimension once Emperor Geldoblame collected all the End Magnus cards and summoned their power. Cor Hydrae appears at the "center" of the sky while armies of monsters fly from the massive fortress to each continent, wreaking havoc on the entire world. Cor Hydrae is protected by an energy barrier that prevents it from being attacked. The leaders of the world meet in Anuenue to find a way to destroy the barrier, and so, they decide to use the power of the End Magnus left in each island to launch an attack to the castle.
After the attack, the barrier finally breaks and the heroes enter to the fortress. There, they fight the five Sibling Gods and have the final battle against Malpercio. After Malpercio is defeated, Cor Hydrae begins to crumble and is sucked into a dimension of pain and suffering, where it it destroyed along with the Dark Brethren for good.
Although Cor Hydrae doesn't appear exactly the same, in Baten Kaitos Origins, Milly states that Zaurak Keep looks identical to the illustrations she had seen of it at school and that it is also called Cor Hydrae, revealing that Zaurak Keep was the original name of the stronghold prior to its exile to another dimension.