Ley Lines

There are a bunch of versions of ley lines.

1. Dragon Lines, ala Feng Shui. These lines are natural lines created by the movements of energy deep in the ground. They can be redirected by stone or trees. This means you'll need to be careful about where you build your houses, which way the doors face, where you plant groves of trees and crops and whatever. Rerouting a river can do immeasurable damage to the ley line, and that results in all kinds of nasty shit. Angry ghosts unable to cross over to the other side, teleportation blocks, maybe portals pop up places. Furious elementals as the natural forces fall out of balance. Inexplicable storms, crop failures, earthquakes, that kind of thing. Geomancers are a prized part of society. Many are mages, but certainly not all. Some are just learned and specialize in advising farmers and villages on the proper care of their ley lines - where to plant, where to build. Where to place a single brick, maybe.

2. Ghost Lines, powered by the dead. These Corpse Roads are the lines the dead walk along to get to their eventual return. Strange shit happen all along the line, but it's mainly benign. However, every once in a while a necromancer or demon or something gets in the mix and starts perverting the Corpse Road to its own purposes.

3. Blood Lines! This kind of ley line is the purest expression of life, for all that's good about it and bad. They're usually pretty low-key, but enough living things along that line can create massive reserves of power for a talented blood mage. The death of enough people in an area, such as from a war, a mass sacrifice, a tragedy, these can 'supercharge' a ley line and make a ton of magical power available. As well, some ley lines are engineered by mages to collect their power. For example, a commuter train line built along a ley line moving tens of thousands of lives a day can generate immense power.

4. The ones you want to look out for are the Faerie Roads. These are the paths over the hills and through the woods on which the fair folk tromp. Crossing these lines can give you a bit of a staticky tingle, but beware walking along them. You could find yourself a hundred miles away from home in a day, or lose time, or worst of all: wind up in the fair folks' lands. Natives know exactly where these roads are, and know not to go near them when faerie lights appear there at night.