Sudenkuoppa

Sudenkuoppa is a type of horizontal spatial anomaly associated with some natural spirits. It is technically a spatial magic, but mostly only mastered by those affixed to green magic.

Mechanics
A sudenkuoppa is a spatial loop which traps living beings inside of it. The insides of Sudenkuoppas are devoid of any trees, rocks, bushes or flowers. They often visually seem like perfectly circular forest openings.

Sudenkuoppas can only be created inside of a perimeter defined by at least three trees. The inside of this perimeter doesn't have to be barren. The size of a Sudenkuoppa is only limited by the amount of magic that its creator can output. The inside of this perimeter becomes 'blank', and begins to loop in on itself.

The edges of Sudenkuoppas seem to move around along the position of the beings trapped inside of them. While it's possible to reach the edge, it will slowly inch away. The perimeter can be artificially extended by beings inside of Sudenkuoppas, by cutting or burning down the perimeter trees. The perimeter will always connect to the closest tree

The insides of Sudenkuoppas will always physically remain within the real-world location of the perimeter.

The trapping mechanism is based around the presence of roads. A non-magical being without the ability to teleport can only exit a Sudenkuoppa by gaining a direct line of sight of a road, and then walking over to it without loosing line of sight for more than half a second at a time. If line of sight is lost before reaching the road, the being will become re-trapped.

Strategies for escape
The best method for escaping a Sudenkuoppa is dispelling it. Small Sudenkuoppas (with a diameter of 5 meters or less) can be dispelled with minimal effort by other magical beings.

The most effective non-magical method of escaping is to start a forest fire. This will dramatically increase the perimeter and very likely allow a visual contact with roads. This method can be ineffective in rain forests and Living forests, and is not recommended in protected areas.

The next best method is to manually cut down the perimeter trees. This can be incredibly tedious and difficult, owing to the perimeter's tendency to move away from those inside of it, but it may be the only viable option if magic and/or fire are not available.

Also a good method is to use wireless communications, such as a cell phone, internet or telepathy.

The last possible method is to wait. Sudenkuoppas are semi-commonly used as a deterrent to interlopers, and their creators will likely check them regularly.

Trivia

 * Sudenkuoppa is Finnish for "Wolf's pit".
 * Perkele is notorious for creating Sudenkuoppas.
 * There are incarnations where Piggy has both died in, and escaped from Sudenkuoppas built by Attic Elves.