You can use an action to place this 1-inch pewter Rook on the ground and speak one of its four command words. The Rook rapidly transforms into a square fortress 20 feet on each side and 55 feet high with ramparts armed with 6 Ballista +6 (3d8+4) magical piercing damage. The fortress' AC is 18 and it has 125 hit points and is resistant to all non magical bludgeoning, piercing and slashing damage except from siege weapons. If the Rook is unoccupied the person who speaks its command word becomes the Master of the House. The size, appearance and function of the fortress' interior is determined by the Master of the House. The fortress can be dismissed back into Rook form only when the Master of the House speaks the command word. Each creature in the area where the fortress appears is automatically teleported to the nearest unoccupied space adjacent to the fortress. 

The fortress has the following features:

Castle Rizz: The Master of the House has advantage on all persuasion, deception, intimidation, and performance checks made against invited guests while within the boundaries of the fortress. 

Palatial Prison: The Master of the House is permanently bound to the Rook and cannot leave its boundaries. When the fortress is dismissed into the Rook the Master of the House remains within.   

The Heart of the Bastille: When the fortress is activated the pewter Rook must be somewhere within its walls. If a creature gains possession of the Rook while the fortress is activated they gain the ability to cast Geas at 9th level on the Master of the House. If the Master of the House dies while another creature is in possession of the Rook in this way, they will become the new Master of the House. 

Not in My House: The Master of the House can eject any invited creature from the Rook. The ejected creature is teleported to an unoccupied space adjacent to the fortress.

An Eclectic Dwelling: The fortress can activate in four different modes depending on the command word used. The command words are determined by the Master of the House. 

Wrath: While in Wrath Mode the Ballista have a +8 to hit and fire two bolt burst. All Melee attacks against uninvited targets within the boundaries of the fortress have advantage. The fortress' hit points reduce to 75.

Bulwark: While in Bulwark mode the fortress' AC becomes 20 and the Fortress gains resistance to all damage types. The number of ballista is reduced to three.

Ward: While in Ward mode all invited creatures within the boundaries of the fortress regain 1d6+1 hit points at the start of its turn. When an invited creature is reduced to 0 hit points within the boundaries it automatically stabilizes but does not continue to gain hit points in this way. The ballista bolts can be replaced with a "Salving Bolt" which causes the target to regain 1d6+1 hit points. 

Jester: The Master of the House charisma score is set to 23. If the Master of the House charisma score is already 23 or higher this mode has no effect.