This ancient pit was located on the planet Eternia and had existed for an unknown numbers of years. It was the site where the Evil Horde led by the warlord Hordak assembled his three sorcerers in order to envoke the Spell of Separation. As part of the process, the Triad of Discidium was crafted with the express purpose of transforming one half of Eternia into a dark realm that would become known as the Dark Hemisphere. It was Hordak's belief that his minions would thrive in that part of the world and provide a haven for him where he could continue the conquest of Eternia. But the magics he unleashed proved to be too powerful for him to control and threatened to rip the planet apart. Thus, in order to save himself - Hordak commanded his sorcerers to remove the Triad from the Well of Darkness and split the artifact into three parts thus stopping the Spell of Separation from being completed.
In later years, the Evil Warrior Two-Bad re-assembled the Triad and returned it to the Well of Darkness in order to complete the ritual in the mistaken belief that it would allow Tuvarr and Baddhra to return to their original forms. Their actions were stopped by the intervention of He-Man after he was notified of the danger by the Sorceress of Castle Grayskull. Afterwards, Evil-Lyn with the unwilling assistance of Count Marzo attempted to use the Well of Darkness as a site through which they could bring about the return of Hordak. Learning of this, King Hiss and his Snakemen attempted to stop them but were themselves stopped by He-Man. Afterwards, upon learning of Evil-Lyn's plot, He-Man moved in and prevented her from completing the ritual that would free Hordak from Despondos.