Nazjatar Ally - Poen Gillbrack

Nazjatar Ally - Poen Gillbrack is a currency used in the combat ally system of Nazjatar. Upon obtaining it, it is automatically converted into Poen Gillbrack's experience.

Source
It appears as a quest reward from the following combat ally quests in Nazjatar:
 * Arcane Cache (Horde)
 * Drunk Angry Murlocs (Horde)
 * Feed Them All (Horde)
 * Gather Friends
 * Giant Crab Leg (Horde)
 * Misdirection (quest)
 * Most Delicious Clams (Horde)
 * Poen's Favorite Dish
 * She Sells These Shells
 * Stolen Power
 * The Dark Garden
 * The Heart of the Water
 * To Soar Like a Ray
 * We've Got Crabs!