Balefire Oskill on "Special Helms" : Am I just unlucky?

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Vincendra
Stone Warrior
34 | 0
Ilvl 99 Mask, which according to the game guide is a "special helm". The other base would be a Bone Helm.

I used 300 shrines and did not roll Balefire once, plenty of other Oskills. Am I just unlucky?