I'm on vacation & posting from my phone so apologies if the formatting is even rougher than my (admittedly sloppy) usual.
Above the valley, a snare has been set.
- Triggering the trap, dislodges a wedge that supports a large boulder. With the wedge removed, the boulder falls, tightening the snare noose, and dragging the unfortunate victim over the cliff ledge to the valley floor below.
Ledge: Partway down the cliff, there is a nature ledge.
- Rocky projections on the cliff face form a natural stair from the top of the cliff to this ledge.
- The ledge is split by a crevasse but an acrobatic adept could jump the gap.
- Another rocky stair leads down to the valley floor.
Gallery: On the facing cliff wall, there is another ledge protected by outcroppings. The ambushers are likely to be waiting here to attack anyone caught by their trap.
- Ambushers can attach with ranged weapons from good cover.
- Boulders have been staged to roll down onto the valley floor. On the map, I drew in zones on the valley floor corresponding to the areas threatened by each boulder.
- A stairway leads down to the floor and a tunnel provides an easy escape.
- Rocks and ranged weapons can be rained down from above.