Daern's Instant Fortress is a rare magic item from the Dungeon Master's Guide (p. 160):

You can use an action to place this 1-inch metal cube on the ground and speak its command word. The cube rapidly grows into a fortress that remains until you use an action to speak the command word that dismisses it, which works only if the fortress is empty.

The fortress is a square tower, 20 feet on a side and 30 feet high, with arrow slits on all sides and a battlement atop it. Its interior is divided into two floors, with a ladder running along one wall to connect them. The ladder ends at a trapdoor leading to the roof. When activated, the tower has a small door on the side facing you. The door opens only at your command, which you can speak as a bonus action. It is immune to the knock spell and similar magic, such as that of a chime of opening.

Each creature in the area where the fortress appears must make a DC 15 Dexterity saving throw, taking 10d10 bludgeoning damage on a failed save, or half as much damage on a successful one. In either case, the creature is pushed to an unoccupied space outside but next to the fortress. Objects in the area that aren't being worn or carried take this damage and are pushed automatically.

The tower is made of adamantine, and its magic prevents it from being tipped over. The roof, the door, and the walls each have 100 hit points, immunity to damage from nonmagical weapons excluding siege weapons, and resistance to all other damage. Only a wish spell can repair the fortress (this use of the spell counts as replicating a spell of 8th level or lower). Each casting of wish causes the roof, the door, or one wall to regain 50 hit points.

I want to know if it returns to cube form when dismissed, or just goes poof. Is there perhaps something I missed in the description?

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    \$\begingroup\$ For what it's worth, our group recently learned that the fortress is not reusable if you accidentally place it on unstable ground above a mile-deep pit. (It's ok, it helped us kill a lich, so it was worth it.) \$\endgroup\$ Jan 20 at 17:39

2 Answers 2



What does dismiss mean?

From the spell find familiar, we know that 'dismiss' by itself does not indicate whether the action is permanent:

As an action, you can temporarily dismiss the familiar to a pocket dimension. Alternatively, you can dismiss it forever.

The word 'dismiss', by itself, does not tell us whether something goes away permanently. The word dismiss requires a modifier - either an explicit one, as in the find familiar spell, or an implicit one. In the case of the fortress, the implicit modifier can be derived from the context surrounding the use of magic items.

What is a consumable?

DMG 141:

CONSUMABLES. Some items are used up when they are activated. A potion or an elixir must be swallowed, or an oil applied to the body. The writing vanishes from a scroll when it is read. Once used, a consumable item loses its magic.

DMG 135:

The value of a consumable item, such as a potion or scroll, is typically half the value of a permanent item of the same rarity.

DMG 139:

Potions are consumable magic items...A scroll is a consumable magic item.

DMG 214:

Most sentient items are weapons. Other kinds of items can manifest sentience, but consumable items such as potions and scrolls are never sentient.

In context, we can assume that a potion (including oils and elixirs) or scroll is a consumable magic item unless otherwise noted. We can also assume that any other magic item is not a consumable item unless otherwise noted.

The fortress is not a consumable

The Bird version of Quaal's feather token says:

You can dismiss the bird as an action.

How are we to know what dismiss means here? By looking at the rules for feather tokens, which say (DMG 188):

Different types of feather tokens exist, each with a different single-use effect.

Because the rules for feather tokens call them out as single-use items (consumables), we know that when we dismiss the roc from a Bird token, we will not get it back.

In contrast, nothing in the description of the fortress indicates that it is a consumable or single-use item. Because we can assume that non-potion, non-scroll items are not consumables, we can be confident that "dismissing" a fortress is not permanent. Rather, 'dismissing' it results in the fortress shrinking back down to its original cube size so that it can be transported and re-used. This is, in fact, why it must be empty to dismiss it - otherwise, anything inside it would be crushed. It is also unlikely that rules for repairing it of damage would exist if it were meant to be used once and then remain in place or disappear permanently.


It is reasonable to assume so

However, there is nothing in the description that actually says. A reasonable DM could rule either way, and still be "within the rules".

My assumption has always been that it returns to a cube and can be re-used, and in games I've been in, that's how we've played it, but the description does not actually say that.

You can make an argument that other magic items of roughly equivalent utility are generally re-usable, and you can note that magic items (such as magic ammunition, for one example) that are one-time use typically say that.

Furthermore, you have to empty it to dismiss it, which makes sense so that it can't be used for storage, perhaps.

But those are just arguments, there's nothing definitive that says.

Of note, in D&D Beyond, it does not have the "consumable" tag.

  • \$\begingroup\$ Good point about the consumable "tag" on DDB - that is a source of information I didn't consider. \$\endgroup\$
    – Kirt
    Jan 19 at 6:15

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