Locus

The planetoid known as Locus is rare and only appears to certain individuals. Many view it as an omen, but very few know its true origins. It is directly tied to the plane of Pandemonium and the Astral Sea. There are orders that have sprouted up in its worship, although they have kept themselves cloistered. Others believe the Moon is shown to people who must make a difficult choice in the future that can sow change.
Locus is truly the conduit for chaos and prison to the Titan of Chaos known as Entropy. Long ago Tempurus, the Time Keeper tried to kill Entropy, but instead realized that in killing Entropy he would ultimately kill himself, so instead, the Time Keeper trapped the Chaos Titan, keeping his energy alive but channeling it mostly into the Astral Sea and Pandemonium. Without Pandemonium or Locus, the chaos Titan could be freed. Zaridun, The Changer of Ways contemplates and pushes for this freeing of Entropy. 
The moon reveals itself to people who stand to change the order of the world, and sometimes will show itself to people touched by Zaridun, The Changer of Ways or even The Ambassador, both thought to be children of Entropy. Whether this change is good or bad does not matter to the Titan of Chaos.  
Locus, as well as the other moons, are thought to also act as conduits or both Arcane and Divine magical leylines, sort of acting like a magnifying and passage way for the magic to flow through the material plane.

Type

Planetoid / Moon