A Chaos Sphere is a source of tremendous raw power, which is used by the Serpent Riders in their conquest throughout the Universe. These artifacts are the three brothers' most prized possessions.
The full extent of the Chaos Spheres' power and their specific abilities are not known, yet it is said they possess great power to create or destroy.
D'Sprail's Chaos Sphere is never seen in-game or anywhere else. It is not known if he even possessed one. If he did, its fate remains a mystery.
Korax's Chaos Sphere appears during the game ending text screens. It is hidden in an unspecified place, which could be a pocket dimension of some sort or one of the Outer Worlds. The entrance to this place is in Korax's own lair and will not open until he is killed.
When the player first approaches this Chaos Sphere, it will play a trick on him and sends him into the Realm of the Dead. If the player manages to fight his way through this realm and return to the Sphere, he is supposedly able to claim the Sphere as his own. Its fate from this point onward is unknown.
Eidolon's Chaos Sphere appears in the game itself. It is brought into the battle once its master is wounded by the player and recharges Eidolon with energy, which also make him grow larger in size and wield more powerful spells.
The Sphere is eventually destroyed by the player, which also allows him to slay Eidolon. Themedes of Mur warns that if even one piece of the Sphere exists, so does great evil. It is unknown if this is a hint that a fragment of the Sphere survived...