The Hell Caster is a boss in SAS 4. See the page Chaosblade for some background info.
Health: 100,000 normal, 300,000 savage
melee damage: 3,000 normal, 10,000 savage
ranged damage: a shear arc of pure chaos 7,500 normal, 20,000 savage
melee range: 5 meters
ranged attack range: 15 meters
only found in the mission; Journey to Hell