Konahrik
A heavy mask. When your health is low it may heal you and blast nearby enemies with fire, and now and then it calls a spectral Dragon Priest.
Where to get it
Set the eight named masks of Skyrim on the shrine in Bromjunaar Sanctuary and the dragon head at its centre opens.
Found in Labyrinthian.
Can be missed
Needs Nahkriin, which can only be taken during the one visit to Skuldafn.