In a Middle Earth type world, there exists a magical map. It has the property that anything that happens to the map also happens in the real world.

The map can be 'zoomed' in or out to get the right level of detail. The best resolution would be as shown in the following map. You can see the scale in the bottom right under the coat of arms. There is a black and white line the total length of which is marked as 200 yards.

The obvious problem

Given that changes to the map affect the world it represents, the owner could in theory cause instantaneous catastrophic effects by tearing the map in half or scribbling all over it.

I'd like to be able to change the course of rivers, or make bridges collapse in a natural-seeming way. However I don't want to simply draw a mountain and have it suddenly appear out of nowhere.

Question

What rules can I make in order for the map only to cause changes that seem natural and possible to the inhabitants of the land and that happen at a reasonable scale and in a reasonable space of time? I don't want the owner to have to be an expert artist or map-maker.

The effort you have to put into altering the map is directly proportional to the effort it would take to apply that change to the reality.

To give you an example, removing part of a forest will be easier than deviating a river which will be easier than rising a mountain range.

If you don't have the right amount of force or stamina you simply cannot even think of performing certain tasks.

Side effect: forget about folding the map, unless you are a tectonic plaque.

Add a user interface

Just like I can't erase a program from Windows by rubbing an actual eraser against the screen, so too will the map answer only to commands it understands. A drag and drop interface would be nice.

Otherwise make it require some special ink or pen to operate it. These can be enchanted so that you can draw a decent river on the map even if you can't draw stick figures by yourself.

Tearing the map into pieces will not tear the land, it will just destroy a really useful magical device.

Anything that happens to the map happens to the real world... eventually. Changes to the map simply put the world on the path to reach that change, and naturally the more impressive changes take a long time to happen.

• Draw a new patch of green behind your house, and spend the next few minutes wondering how you never noticed that big tree in your backyard.


• Draw a fine villa on the edge of town, and magically the paperwork for it is approved and the builders are paid for. Construction should be finished by the end of the year.


• Draw a new river and over the next few months a series of severe rainstorms or a newly constructed dam causes a lake to overflow, creating the river.


• Draw a new island in the middle of a bay, and soon enough you feel the earthquakes caused by the new volcano that slowly forms the island over the course of a few millennia.


• Rip the paper in half, and a massive asteroid is set on an eventual collision course with the world.

So, if someone wants to cause a major catastrophe or otherwise significant change to the world it's unlikely that they live long enough to see it happen, and gives plenty of time for the change to be corrected by someone who wants to preserve the world.

As my 6 year old son observed, all magic systems are about manipulation of energy.

The map acts as a user interface for managing the energy to alter the landscape, but there is a finite amount of energy available to work with.

What is the energy source? Does it draw on the energy of the "earth"? The energy of the user? Or some other energy source like a trapped demon?

It takes energy to manipulate large amounts of energy. If the map directs say the entire energy of the world, it uses energy from another more manageable source to direct it. Does it draw from the map's user? In that case the possible changes would be in proportion to the energy that can be provided by the user.

If the user requests a change that is beyond the available energy limits, then the map either rejects the request and returns to whatever state it was in before the request, or it attempts to fulfill the request and self corrects to match what really happened afterwards. If the map sets of something bigger than what was intended, it also self corrects afterwards.