The Lookout Post is a trap that is sometimes encountered in the game.
The Lookout Post (or Sentry Post) is a small defended strategic point of the Undead Army.
There is usually some type of Hazard like a Chasm or a bank with Stakes in front of the Lookout Post. There is always one or sometimes more than one Archer Skeleton or Armored Archer Skeleton stationed. There are also always Skeleton Fire Pits that deploy extra Skeleton reinforcements.
For a list of other types of dangerous trap see: Hazards