This extremely dense palm-sized metal cube radiates intense magic. When placed on the ground and activated by word of command, an adamantine fortress emerges from the cube after a number of rounds equal to the strength of the item. (Anyone who remains standing in the space where the fortress emerges suffers 1d6 Force damage per strength of the item and is flung prone one encounter space into the air.) The fortress has a number of floors equal to the strength of the item; each floor's walls are equal to 2 personal spaces in height and 1 melee space in diameter, and contain a single arrowslit aperture on each floor. The fortress is accessible by a single, magically sealed door on the first floor that opens by word of your command; it may only be forced open in a contested spell check against you, using an Arcana skill of your choice. Additionally, the walls of the fortress are immune to mundane weapons and can only be damaged by siege weapons or magic (the fortress has the equivalent of an airship's 5 AP).