An idea for replacing the Greater Demon:

Shadow Titan (or Shadow Colossus, if we want to avoid a direct comparison to the existing Titan)

Race: demon

Body: 10 to 20 meters tall, humanoid, with a large dragging tail. Large hooved feet, walks upright with a slow, ponderous gait. Skin is scaly, with an ashy black color, but reflects light with a metallic glint.

Head: A large, wide, lizard-like head, with unlidded blue-glowing eyes, and rows of sharp teeth.

Armor: No heavy armor, but their skin is covered in tightly overlapping scales, like that of a dragon. In wartime, they appear to wear an unbelievably large black cape, but instead of fabric, it's just a wreath of choking black mist.

Armament: Wields an immense black sword of blunt iron, but uses it more like a club than a real sword. Slow attacks deal immense physical damage. Will use its clawed hands just as readily as the sword.

Spells: Does not cast spells per se, but it's mere appearance will cast fear into the hearts of mortal men. Has a tendency to make the room darker, but it's not clear if this is a physical or psychic effect.