Traps are a special type of defense that can be used only a single time on each battle.
Traps are hidden defenses that are triggered by enemy troops when they enter on their trigger zone.
The biggest difference from other defense is that the enemy can't see the trap and its location until they are triggered, they are invisible until they are activated.
There are currently 7 traps on the game:
Each trap can be used only a single time on the battle. For example, once triggered the Giant Bomb will explode causing damage to enemy troops and will not be re-armed during the battle.
Friendly Clan Castle troops do not trigger traps.
Traps are not considered buildings on the game. They are not required to be destroyed to get 100% and they don't use block the deployment of enemy troops. For example, if you have an open space in the middle of the village placing a trap on it will not prevent the enemy from deploying troops on this gap.
After being triggered, all traps are useless until they are re-armed. This happens in different situations, depending on the game mode.
On the regular multiplayer the traps are re-armed when the user logs in. For example, if you are attacked and a trap is triggered, it will not be armed on the defense unless you open the game. This is why abandoned villages with deactivated Inferno Towers and X-Bows usually don't have traps as well.
However, on Clan Wars, Clan War Leagues, and Legend League, the re-arm happens automatically when the battle is over, regardless of the player opening the game or not. With this system, it's 100% guaranteed that all traps will be armed and ready to be triggered when attacked.
There is no longer any cost to re-arm traps, it's 100% and automatic.