Multiplying Brick, A System-Agnostic Magic Item

Multiplying Brick

Description:  Rough red brick inscribed on every surface with arcane sigils.  Magical senses reveal a strong conjuration aura.  More elaborate investigation spells indicate that some of the sigils spell out a pair of command phrases and shows that one face has a clear "This Side Up" rune upon it.

Powers:  Once from one dawn to the next, place the brick face-up on a solid surface, speak the first command phrase, and in an instant the brick multiplies into a double-layered mortared wall about 7" thick.  Creatures in the way of the wall are harmlessly forced to a random side of the wall.  The bricks spread out from their origin point up to 40' wide in search of anchor points which it magically bond to, then fills as much vertical space as it can to a maximum of 400 square feet and a maximum of 20' in height.  If unanchored at both ends, the wall is unstable and can be pushed over with a medium-difficulty feat of strength, although it falls slowly enough that creatures on the other side can move out of harm's way unless immobilized.  Otherwise it requires an extremely difficult feat of strength to break through or five minutes of work with suitable tools to make a man-sized breach.  As a rough brick wall it's not very hard to climb if there's a gap at the top, of course.

The wall (or its remains, if broken up by force) vanish at the next dawn, or when the second command phrase is used.  The first command phrase cannot be used the same day if the wall was left up until it expired, but will become available at the next dawn. 

Possible Origin:  Multiplying bricks were originally the product of Dwarven mason-sages, but their formula is widespread amongst the broader community of alchemists and artificers.  They require a great deal of time and effort to create and are corresponding precious.

Complications:  The item is no more resistant to damage than an ordinary brick and is often left where an enemy can get at it easily.  Moreover, it stands out from the rest of the bricks in the wall due to the sigils covering it, although spotting them without a careful search is unlikely.  Magically sensitive creatures will easily spot it as the nexus of the wall it creates, the rest of which registers only a weak aura of power.

On the plus side, the command phrases are on the "Face Up" side and cannot be read while the wall is intact.  On the down side, did you remember to write down the command phrases so you can use them to lower the wall when desired, right?

Design Commentary:  A handy delver's tool that can really change the situation in a fight or escape, but it may not be something you get repeated uses out of unless you're careful.  You might very well have to face an enemy who picked up your own brick and uses it against you in a later encounter.

And that wraps up the week's Dwarven magic item focus.