Resistance to Fire and Heat: Class 5000. Surtur is made of fire.
Invulnerability: Shift-Z resistance to Physical, Energy and Magical attacks
Energy Sheath: Shift-X. Surtur's fiery body provides Shift-X protection from blunt, edged, and shooting attacks.
Fire and Heat Control: Surtur can control fire and heat with Shift-Z ability.
Phasing: Monstrous
Shapechange: Monstrous
Retarded Aging: This power grants Class 1000 immunity to the ravaging effects of time. Surtur only physically ages one year for every 1000 years. He will age, just very slowly. They may still be killed normally.
Equipment
Twilight, Surturs "Sword of Doom": Class 1000 material. Can do Shift-Z damage. Surtur can gain Class 3000 flame damage by Igniting his sword in the "Eternal flame of Destruction".