The Cloak has the hide ability, which makes it invisible to enemies after it moves. However, the Cloak is visible upon being trained, capturing a village, or exploring a ruin. A Cloak can also be revealed when an enemy unit attempts to move onto a tile containing an invisible Cloak; this allows the enemy unit to attack the Cloak. Moreover, units with the detect ability can detect Cloaks; a small dot will appear on the unit's icon.
The Cloak's power lies in its infiltrate ability. The Cloak can "attack" an adjacent enemy city, which spawns Daggers within the city's borders and consumes the Cloak.