Within the Northern Forest (and in Narthaven), the PCs have run into an odd form of undead monstrosity. Creatures animated in this fashion have both a corporeal and incorporeal version of themselves animated. Their physical forms seem to be somewhat under the control of their ghostly ones, the latter of which retain the memories and experiences of their former lives.
The players first encountered these undead within the town of Northaven, desolated by the white dragons living within the six peaks.
The players next encountered a pack of undead trolls, animated in similar fashion, in the Northern Forest (south of the Six Peaks), when questing for the first gem of the Demon-Knight’s staff.