The Sillwatchers is an organization dedicated to protecting Aslea against extraplanar threats and incursions.
They exist to safeguard the structural integrity of the prime material plane.
The Sillwatchers were founded by Dewaard, the first Mistwalker. As part of The Ark, Dewaard granted The Sillwatchers a vast amount of power and deference to accomplish his objectives. The Sillwatchers operate in general secrecy but are known, respected, and welcomed in all of North Alstone. To meet a Sillwatcher is a rare occurrence, and they generally do not give many reasons as to why they have arrived or what they plan on doing. Their influence extends far beyond the prime material plane, where their activities are largely begrudgingly accepted by the rulers of other worlds, lest they bring the wroth of The Ark down upon themselves.
The Sillwatchers are divided into small, well-rounded teams of adventurers, many of whom have bloodline or magical connections to the other worlds of Aslea. Each Sillwatcher team is composed of a Mentor, an Investigator, and an Enforcer, each with their own powers and abilities to execute their role. The organization is led by the Sovereign Walker. The true identity of the Sovereign Walker is a well-kept secret, even from members of The Sillwatchers themselves. Many adversaries of The Sillwatchers are skilled in the ancient art of Onomancy, whereby the True Names of beings gives you some measure of power over them.
While The Way Between the Worlds is closed to all of us in Aslea, The Sillwatchers seem to possess the ability to travel across vast distances, and even other worlds, with relative ease. This suggests that The Ark did not completely isolate the material world of Aslea from the rest of the planes. Such a thought is horrifying, to say the least, given the horrors that lurk deep in the far realms, waiting to devour us all.
-excerpt from "The Ruminations of the Far Flung Almost Hopeless Secret Secrets of Aslea",
written by Loman Kelfis, dwarven scholar