The Helmet of the Old Gods is a reward for completing No One Escapes Cidhna Mine.
Wearing this piece of armor grants the following bonuses:
- Fortify Magicka: 30 points
This means the helmet cannot be improved past flawless quality without boosting the Smithing skill over 100. This can be achieved by using enchanted items and/or blacksmithing potions to fortify Smithing.