In between the PC's seemed vexed, confounded, and felt railroaded. But they have patience. The proper response when confronted with the inexplicable and decidedly deadly. I found it a good session because the PC's felt unsure and nervous while I don't think I abused their fantasy sensabilaties.
I did throw many rolls on them, in the form of saving throws. I like it better than rolling against ability scores because it rewards levels. Maybe the PC's would argue the case, but lifting a portcullis together and then one bolts, roll against Save vs. Paralysis. Didn't make it, ouch. Forget the strange serpent with the pig face snorting through the underbrush where the heck did the dwarf run off to?