The Trapped Circle
What the heck does that term mean anyways? And why wasn't it in the Core book?
Creatures of Darkness:
(from a sidebar that apparently will exist in the Dragonblooded book)
Creatures of darkness are foes of Creation who stalk through the night or dwell in the dark places of the world. This includes demons and undead by default, but the Storyteller is free to include or exclude beings from this category at her discretion. A benign ancestor ghost might not be a creature of darkness, while a subterranean monstrosity empowered by forbidden gods could be.
2e Core pg. 192
Some Charms have special effects against "creatures of darkness." These are enemies of the world, so named – where judgement is required- by the judgement of the Unconquered Sun. These include, but are not limited to: Yozis, demons, Neverborn, walking dead, ghosts, Deathlords, unshaped fair folk, Abyssal Exalted, and Infernal Exalted. The Storyteller can make exceptions or add other groups to this list that might be appropriate. A sympathetic ghost might not be a creature of darkness, while a horror that eats at the world's heart might be.