Skeleton Traps are structures that remain hidden until they are activated by an attacking troop moving into their trigger radius.
Once triggered, the coffin rises from the ground and multiple Skeletons appear in the area around the coffin to attack nearby troops depending on whether it is set for ground or air troops. You can see the difference above using the Toggle Mode feature.
They can be configured to attack either ground troops or air troops.
They will remain invisible if set to ground and an air troop passes over (and vice versa).
The number of Skeletons released depends on the level of the Skeleton Trap.
The Skeletons released have a small skull icon next to them to signify they came from a Skeleton Trap (as opposed to being summoned by a Witch), similar to the icon displayed next to Clan Castle troops. The reason behind this is because they play an equal role to the Skeletons summoned by a defending Witch in the Clan Castle.
The Skeletons from the trap have exactly the same stats as the Skeletons summoned by the Witch.
Skeleton Traps set to defend against air troops have wings instead of a skull on the face of the coffin. Skeletons that arise from being triggered while set to defend against air troops float through the air with the aid of two small red balloons, the same balloons as those on the Air Bomb.
Skeleton Traps were added in the 2014 October 22 Halloween update, but are a permanent addition that will remain available after the holiday has passed, unlike in previous years.