The Deep was an ancient power composed of millions of trapped souls ruled by a single, ageless entity. It was a source of great evil in the Metaverse. It was opposed by the Cosmic Wheel Continuum.
The Pyramid of Simhaya
The Pyramid was a piece of extremely advanced technology that acted as a storage center for the Deep. Early in the Deep's history, the beings who unleashed Simhaya discovered how to remove the soul from the body, thus making it immortal. The Pyramid was once known as the House of Ascension. It was a massive pyramid made of a black mineral (around 333,000 ft. tall). In it were remarkably advanced computers, storage chambers and Technurgical apparatus. When Simhaya entered the Central Dimension, he destroyed the creators of the Pyramid and used its power to enslave the souls of all inhabitants of that planet.
From the Pyramid, the Deep makes its plans and generates its Manifestation, the combined psychic presence of Simhaya and the souls that makes the Deep so intimidating.
Simhaya was an entity of great power and knowledge. In the ancient days of the Metaverse, he ruled the Central Dimension. Power eventually corrupted him, and he sought to take the Higher Dimension, all the while cosmically tightening his grasp on the worlds of the Central Dimension. He was defeated by the Source and imprisoned in the Western Dimension. The inhabitants of Klaloc sought to unleash him and gain his power, but he easily overpowered them.
From then on, he continued his goal to control the Central Dimension and eventually, the Metaverse. He has been nearly everywhere, but entities of Earth know him by various names: Semihazah, Satan, Lucifer, Angra Mainyu, etc. Not every myth about evil beings in religious traditions was influenced by him, but he is behind many.
What Simhaya does not realize is that the Source is infinitely more powerful than he. He continues to fight a losing battle, but his victories are costly for the forces of light.
The Deep Manifestation
When Simhaya siphons the power of his captured souls, and gains their conscious minds within his own, he speaks with the voice of the Deep. His form becomes far more terrifying, he gains power and he can see farther across space than with his own eyes.
Simhaya rarely appears to mortals outside of his Manifestation, unless he is seeking to be discreet.