The Epiphanies of Guidance are an entity from the Star Ocean that manifest themselves to the Cardianon. It is a floating object that is diamond shaped. It makes whoever uses it feel like a God. The Cardianon did not know it but they were being controlled by them and became hostile creatures. They were transformed by it and even the leader of the home planet of the Cardianon.
In the story they feature near the beginning of the game. They first appear on Lemuris. It is the cause of a disease called Bacculus, which plagues the village of Triom. It is used on the Celestial Ship to transform the Cardianon into creatures and attack the crew of the ship. It was brought down to Lemuris when it crashed. It is destroyed just after it summons a monster to its aid.
Later on in the game when the party are drawn to the planet Arcturis VIII. They discover it is on the ship via computer, which Faize hacks. After some venturing throughout the ship they actually find the Epiphanies of Guidance and Bacchus destroys it. The leader of the ship arrives and broadcasts his need for God status and how the Epiphanies give it to him. His mobile transport system is transformed by the Grigori into Sahariel. When he is defeated that is all of the Epiphanies the Cardianon have gone.
The third encounter with an EoG is on Aeos for the second time. When they have defeated the Phantoms that have infested the planet they set off for a cave that is rumored to contain a Grigori. Arumat P. Thanatos joins the party and raises their suspicions and they set off for said cave. After trawling through the long cave the party reach a giant dead snail. Although behind it lies an EoG which inevitably transforms it into a Grigori monster, Armaros Manifest.