Chaos Sphere

Additionally, an artifact known as the Chaos Sphere has at times been used, mainly in Hexen and Hexen II, as a source of extra power for the Serpent Riders. The Sphere plays no active role in the battle against Korax in Hexen; however, in Hexen II, the player will encounter it after defeating the smaller and weaker form of Eidolon, causing the eldest [Serpent Rider to grow to mass proportions. It has 2000 hit points here, and must be destroyed; otherwise, Eidolon will remain invulnerable to any attacks.