The Great Abyss is the manifestation of the infinite expanse of space in the Animare. Basically, it is the great nothingness that surrounds the planets and is considered to be a unique somewhat separate layer of the Animare that separates one planetary spiritual ecosystem from another in the same vein that the Horizon separates the material world form the Animare. However, in difference to the Gauntlet that merely acts as a separator and "catcher" barrier, the Great Abyss presents to have a mind and ecosystem of its own, parting primarily by having its own inhabitants the Atramenta, Itself is thought as a void realm of near nothingness that tends to shifts violently and create its own ecosystems in small pockets called Nebulae, thus the Great Abyss is not only seen as merely a great nothingness but also as a pilar of creation, a cradle of life and death, of nothingness and everything, of chaos and orderly stillness.
To tap into the domain of the abyss is to tap into this paradox and to attract the gaze of its disturbed mind. Abyssal legatees tend to have powers on stillness, dark energy, primordial alive darkness and a limited control over creation and nullifying.