Nethershard

Nethershard is a currency used to purchase items sold by the Captive Wyrmtongue at Illidari camps in Stormwind, Orgrimmar, and Legion Invasion sites, as well as several vendors on the Broken Shore.

Specifically, they are crystalized fragments of residual nether energy, a solidified form of the Twisting Nether itself.

Source
The currency may be accrued in a number of ways.
 * Complete certain world quests in a Broken Isles zone while it is under attack from Burning Legion forces.
 * Complete one-time Broken Shore quests.
 * Kill demonic mobs in Broken Shore.
 * Loot treasure chests in Broken Shore.


 * Loot from Legionfall Recompense, awarded upon contributing 100 Legionfall War Supplies to the construction of a Legionfall building. (This is repeatable.)

History
Nethershards dropped from the Legion commanders, barracks commanders and their command crystals during Stage 3 of Legion Invasions. They were also contained in stacks of five and ten from Small Legion Chest and Large Legion Chest, respectively.

While Nethershards did drop for players below level 98, only the Felbat Pup was available for them to purchase.