There are no breadcrumb quests leading up to this one.
Vestige is located due south of Erathis Menel. The Force Core can be found on the second floor of a burned out house on the northern edge of Vestige. After obtaining the force core you will need to interact with the Planar Reactor which is located inside of the large building in the middle of town. After completing these two steps return to Erathis for your reward.