Going to have to reread this and the bonus adventure as this leads me to think about adding an inquisitor sent after Malefex so your PCs can rescue their mentor witness a truly scary recurring nemesis and figure a way to hide the true nature of the lost shrine to insure the Empire/first order doesn't blow up the place!

Maybe have Malefex captured to become eventually the PCs nemesis once they get to the end of the bonus adventure?

Anyway thanks for the heads up!

Huh!

Perhaps the truly scarier part is having the Inquisitor ally with your PCs to fight the bad guy just to emphasize how truly scary that opponent is?