Lodestone is a giant stone of pure magical energy. These were left on planets by the Old Ones. They are dangerous to planets in the hands of the Demonata as they can be used to make Tunnels from the Demonata universe to the Human universe.
Known locations of lodestones
There was a lodestone under Carcery Vale deep under ground in a cave. This was used to create a tunnel years ago which was successful for a short while until Drust and Bec stopped it. It was opened later by Lord Loss because Bill-E let Loch Gossel die. Here is where the Disciples first sighted Death.