The Ledge (5e Hazard)
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(Alternative name: Democracy Ledge, or Anarchy Ledge)
An apparently-easy-to-climb mountain path, just wide enough for a Medium creature to walk up it comfortably, that serves as a shortcut. However, every step incurs saving throw after saving throw as a crowd of inner voices attempt to trick, persuade, or coerce the walker into jumping back down.
There are seven saves in total, and the path switches back on itself; failing a save makes the creature jump, slide, or tumble back down the path, while a successful save allows the creature to proceed for 5 feet. Lawful-aligned creatures have advantage on these saves.
The first saving throw uses Intelligence and has a DC of 8; the second uses Wisdom and has DC 10; the third uses Charisma and has DC 12. Failing any of these saves sends a creature back down to the start of the path.
At this point, the path switches back on itself, affording the walker slight insurance against losing all of its progress.
The fourth save uses Charisma and has DC 14; failing this sends the creature back to the start. The fifth uses Wisdom, has DC 16, and sends the creature back to the spot of the second save on a failure. The sixth save uses Intelligence, has DC 18, and sends the creature back to the third save.
The seventh and final saving throw uses Wisdom, and has a DC of 20. On a failed save, the creature falls right off the path and lands in a heap, taking 2d6 bludgeoning damage from the fall.
If a creature successfully walks up the path, that creature gains a permanent +2 bonus to Wisdom saving throws.
A creature can theoretically clear the ledge in one turn if its walking speed is high enough, but using the Dash action to try and sprint ahead results in the creature falling off the path and taking 1d6 bludgeoning damage after failing any of the saving throws (or 3d6 if they reach and fail the final save while Dashing).
Flying over or otherwise circumventing the path works, but the +2 bonus can only be gained by succeeding on all the saves.