A narrow trail winds it’s way across the face of the mountain, with steep drops on the left.
|Up ahead is a cave inhabited by an anti-social hermit. The trail outside the cave is magically trapped to cause the rocks to reshape into the sheer cliff.
One hundred feet from the cave, a target that makes a successful DC 14 Intelligence (Nature) check notices that about 30 feet of the trail seems “newer” here. There isn’t as much vegetation, as if this area was recently hewn from the side of the mountain.
The trap is triggered when a target enters the new area and travels 15 feet into it. The cliffside shifts, causing the trail to disappear and become a sheer cliff.
All targets in this area may make a DC 12 Wisdom (Perception) check to ascertain that only 30 feet of the trail is changing. Those that are successful may choose to attempt to run to the edge of the trail. All targets in the area must make a DC 15 Dexterity save or fall, taking 10d6 falling damage. Targets that succeed will be left clinging to the side of the cliff. Moving along the cliffside requires a DC 10 Strength (Athletics) check for each movement, with failure resulting in a fall. Those that chose to run for it are safely on the trail, just outside the altered area.
The mountainside resets itself into the trail in 1d4 hours.
A spell such as Detect Magic detects an aura of transmutation on the mountainside.
A spell such as Dispel Magic permanently prevents the mountainside from changing with a successful DC 15 spellcaster check. Effects that suppress magic of spell level 5 or higher cause the mountainside to not change for the duration of the suppression.