Helmet of Ten Storms (tier 2)

The Helmet of Ten Storms is part of The Ten Storms, the raid Tier 2 armor set for Shamans.

Source
Prior to the release of patch 3.2.2, this item dropped from the level 60 version of Onyxia. It has since been moved to Nefarian in Blackwing Lair, along with the rest of the tier 2 helms.