When a Star Falls (2016)

Publisher's blurb:

The Duchy of Jeoff has recently been plagued by a rash of unusually weird and terrible monsters of an unknown sort. This western area, particularly the mountain fastness which separates the Grand Duchy from the Dry Steppes, has long been renowned for the generation of the most fearsome beasts, and it has been shunned accordingly – save for a handful of hardy souls with exceptional abilities and sufficient wealth to build stout strongholds to ward off the attacks of the predatory creatures infesting the rugged lands thereabout.

Within the last few months, however, a walled town not far distant from the area, and four small fortresses as well were destroyed by mysterious attacks! The remaining barons and lords have preserved in brine several partially decomposed corpses found on or near the sites of the ravaging. While these strange bodies are assumed to have belonged to the forces which were responsible for the destruction, the remains were too far gone to learn anything other than they were of creatures heretofore unknown to even the wisest sages of Jeoff. The urgent plea for aid which accompanied these gruesome corpses could not be ignored, and the Duke acted immediately choosing several of his doughtiest henchmen (i.e. your characters) to lead an Expedition to Starfall Mountain.