The three Serpent Riders are as follows: * D'Sparil — Appears in Heretic. Boss of Episode 3: The Dome of D'Sparil. Youngest and assumed the weakest of the three, he has 3500 hit points, and rides a special Green Chaos Serpent with 2000 hit points. He holds a mix of offensive and defensive abilities, one of which includes teleportation. * Korax — Appears in Hexen, at the end of the Necropolis hub. Is the middle age, and assumed to be the middle strongest rider. He has 5000 hit points, but is deemed an easier opponent than the Heresiarch due to his slow movement. He can control various devices and traps in his chambers, teleport in monsters, or teleport himself around at will. * Eidolon — Appears in Hexen II (warning, off-wiki links), at the end of the Return to Blackmarsh section.