Savage Harvest (1994)

Karen and her friends go to her Uncle Gary's cabin in the woods for the weekend.  The cabin is near an old Indian burial ground.  Uncle Gary tells the kids a story of how years ago a medicine man was killed by his own tribe after performing rituals that invoked evil spirits.

Demons are accidentally summoned by touching rocks in the area with strange symbols on them and no one can escape from the woods due to the invisible force field who surrounds it.

This film has long boring exposition, tons of padding,  is kind of tedious, but it's also so ridiculous that it can be awesome at times.