Ethereal Palace

You conjure an ethereal palace in range that lasts for the duration. You choose where it is located. The palace shimmers and glows faintly with an ethereal light. The palace can be placed anywhere within range, including intersecting with solid objects. The palace itself is not solid, instead appearing to be made of a thick mist upon close inspection. However, the windows and doors, of which there must be at least one, may be passed through by creatures from the material plane as though they where the windows and doors of an normal structure.

The inside of the palace is a demiplane which can only be accessed by the palaces' doors and windows. The interior of the palace is warm, dry, and softly lit by glowing magical orbs or floating candles. It is furnished to accommodate the caster and their companions. The caster can arrange the palace to have furnishings and a floor-plan of their choosing, including up to 100 rooms totalling no more than 250,000 sqft (or 10,000 5x5ft squares) and ceilings no higher than 50 ft. The appearance of the palace does not have to correspond to the floor plan; for example, the caster could create a palace with a totally flat floor plan, but choose to have the ethereal palace appear as a skinny tower to the exterior observer.

The palace may be furnished with all manner of tools and facilities required by the caster, such as a forge, a brewery, an apothecary, ect. in order to preform any artisinal downtime activity or for the creation of any item or magic item. Such facilities are also staffed with servants able to assist in such activities.

The palace has at least one exit onto an open "exterior" space that is also part of the demiplane. If not specified, this space can be taken to be gentle, grassy hills with the occasional tree. This space can only be composed of natural features, such as trees, beaches, caves, ect., and it is about 4 sq Km in size, with a misty barrier of force around its edges.

The palace is staffed with servants of the casters' choosing. They can be fey, fiends, constructs, elementals, or humanoids. Regardless of the type or servants chosen, they are artificial life forms bound to the demiplane of the palace and cannot leave it of their own will. They do not age or grow weary while on the demiplane, and if they are brought to another plane of existence, they take 1d12 necrotic damage for each minute they spend outside the palace's demiplane. There are between 50 and 200 servants present in the palace at any one time, depending on the size and needs of the palace. Each servant can perform any task a normal human servant could perform, but they can't attack or take any action that would directly harm another creature. Thus the servants can fetch things, clean, mend, fold clothes, light fires, serve food, pour wine, and so on.

The palace is defended from intruders by 10 guards who have the same appearance as the servants, but use the stat block of the "guard" (MM pg 347) and two leaders who use the stat block of the "knight" (MM 347). These defenders can be instructed to attack any creature who is not the caster, any creature who is not a creature specified by the caster, or any creature who cannot produce a pass-word defined by the caster. However, by default they will only defend themselves, other servants, and the spellcaster from attack.

The caster can also choose to place traps around the palace or fake doors and windows on the outside of the palace that lead trap rooms. Traps can be defined by the spellcaster but they should have a DC investigation check to find and a DC dexterity or arcana check to disarm equal to the spellcasters' spell save DC. a trap should also have a base damage of 5d10 damage of the given damage type.

Creatures who rest in the palace for one week regain all of their hit points, even if they are suffering from a condition that would normally prevent them from regaining these hit points. The effects of curses, poisons, and diseases are suppressed while a creature remains in the palace after this amount of time as well. Creatures do not age while they reside in the palace, and the palace is always able to provide food, clothing, and other necessities to its residents, up to 100 residents. The palace is also able to provide its residents with mundane items that they require, such as ammunition, so long as the total value of items acquired this way does not exceed 500 gold.

Once the duration has ended, the demiplane doe not cease to exist, but the ethereal palace does disappear. Any items or creatures in the palace remain there until they leave. The servants stop regarding the caster as the master of the palace, although they continue to follow the last orders they where given and serve any creatures inside the palace. The caster can no longer change the appearance, layout, or location of the palace until they cast the spell again. Any creature who attempts to leave the palace while the ethereal palace is no longer present in the plane it was conjured on previously will be placed in the nearest available free space to the palace's previous location, although there is a 5% chance (1 on a d20) that they are teleported to a random plane of existence instead.

The only way for the caster, or any other creature, to re-enter the ethereal palace after it has disappeared, is to use the same silver key that was originally used to create the palace. The servants and guards will obey the instructions of a creature who holds the palaces' key, and a creature with they key can make a DC 20 (or the casters' spell save DC, whichever is higher) arcana check to find and open the portal to the palace if they are in the last location that it was summoned to. If a caster uses the same key to cast this spell a second time, they will summon the same ethereal palace, complete with any creatures or items that remain inside.  If it has been more than 30 days since the last time the caster summoned the palace, there is a 5% chance that the spell fails to summon the same palace, and instead creates a new one. In this case, the original demiplane can only be linked back to the key by the use of a wish spell or similar magic.