Hallowed Runestone

Source
This item is a potential reward from the following Class Hall missions:


 * Advanced Taxidermy
 * Dogs of Death
 * Stormy Skies
 * The Nameless King (class hall mission)
 * The Undying (class hall mission)

It is also a quest reward from normal Broken Isles world quests and can be found inside Curious Wyrmtongue Cache.