That orb in Thanatos's chest? That's what this is.
About this creation
The Chaos Sphere is what gives Thanatos the power to transform into his/their different forms. He/They keep it stored inside his/their chest area. The two glowing shafts that are visible in his/their alternate forms channel the Sphere's power so his/their altered state can be maintained for indefinite periods of time. It is unknown if the Chaos sphere can be destroyed. No one has ever gotten close enough to try.