Jack In The Box Trap

The Jack-In-The-Box Trap is available in Dungeon Keeper 2 in versions 1.7 and higher. It literally scares the life out of Imps and also damages enemy Dungeon Hearts.
The Jack In The Box trap looks like a magical item. When Imps try to take it, it jumps up and scares them to death. Then it becomes the Jack creature, which heads directly for the Dungeon Heart. Once there, it explodes and damages the heart and any creatures nearby.
The trap is not activated by any other creature, so they will likely destroy it easily. It can also be destroyed as it is running to the Heart, so it may be difficult to hit. As the Jack cannot attack, it cannot pass through enemy doors, and will stand there until it is destroyed.
The Jack also appears to lose health over time. When the Jack reaches the enemy Heart, it will run around for a few seconds before exploding violently, doing significant damage to the Heart (approximately one-sixth of its full health) and to any surrounding creatures.