Astral Body Interference

Manifestation

The metaphysical law was discovered after attempts to connect clairaudience and clairvoyance catalysts in ancient ruins , in order to get a secured look and hear of them for scholars and others history enthusiasts. This is a service that is given by magic specialists in the field also to help decipher some ancient lore the adventurers would not be able to decipher by themselves. However, the law cames into effect when the place has a high density of restless dead that are stuck, partially or fully, in the astral plane. Those souls are usually devoid of reason and attack anything on sight. since the clairaudience/clairvoyance function as a ghastly connection in the astral plane, present ghosts pass through it and interfere the signal, and even cut it for the most powerful of them. This makes research difficult unless the location is exorcised/purifed of any foreign astral bodies that could create noise on the signal beam.
To deal with this issues, arcane schools and adventuring guilds sometimes loan wondrous items to bring at the sites of exploration in order to either help the capture or exorcism of said ghosts. Because it helps them with their research, the guild/school will give back the loan and usually pay a nice extra for any exploring party that was able to help them secure a connection for their research from afar.

Localization

The manifestation is made only in sites where a huge amount of disquieted ghosts are better, and is magnified the more of them and the longer the site has been haunted. It only affects the Astral Plane connected to the Material Plane,